Breastfeeding-specific multi vitamin supplements are expensive and many mothers want to purchase standard multivitamin and mineral supplements. The standard products such as Sanatogen™ and Centrium™ are suitable for use. It is important not to take products which claim to be high dose and where the recommended daily amount is reported as in excess of 100% on the label.

The only vitamins needed by breastfeeding mothers are vitamin D 10 mcg/day and folic acid 400mcg/day if no active contraception is being used. Normal diets should provide everything your body needs. Remember babies need vitamin D supplements too according to UK recommendations

However, we do know that as a new mum finding time to eat properly can be a challenge and a multivitamin is a safety net.

AVOID dose of vitamin A above 700-800 mcg/day and vitamin B6 above 20-50 mg/day. Iodine can concentrate in breastmilk so do not take levels in excess of 100% RDA.

Omega fatty acids are compatible with breastfeeding

There are no studies on the safety of high dose intra-venous (IV) vitamin drips in breastfeeding mothers. These are purported to cure hangovers, help fight exhaustion, have anti-ageing benefits and to boost the immune system. These claims lack scientific evidence of benefit.

In the absence of a diagnosed vitamin deficiency a standard multivitamin and mineral preparation or a supplement developed for pregnant and breastfeeding mothers, containing vitamin D and folic acid, as above should supply all nutritional needs alongside a healthy diet.

See also factsheet on high dose vitamin D supplements and breastfeeding

High Dose Vitamin D Supplements and Breastfeeding

https://breastfeeding-and-medication.co.uk/fact-sheet/high-dose-vitamin-d-supplements-and-breastfeeding

PDF of this information is available at:

https://breastfeeding-and-medication.co.uk/wp-content/uploads/2023/02/hyperemesis-and-breastfeeding-feb-2023-.pdf

Thank you to everyone on the facebook group who shared their experiences and helped me to update this information.

More women are now breastfeeding their babies for longer and may still be feeding when they fall pregnant. For those who suffer from hyperemesis  gravidarum (HG) this is a tough time. Sadly, some healthcare professionals do not understand that there is benefit to a child from being breastfed to the age of two years and beyond (WHO) alongside a normal weaning diet. Being asked to abruptly wean your older child in order to take medication is not an easy option and is not necessary. Sometimes sitting quietly to breastfeed whilst you fight the feeling of nausea is helpful. Some professionals remain concerned about the teratogenicity of drugs in pregnancy despite national guidance.

“ I had an absolutely awful time while still trying to breastfeed a toddler. The GP refused to prescribe anything other than cyclizine despite me calling them in desperation many times. Nothing else was made available and I was told that I just had to wait until it cleared up.”

Symptoms of NVP and HG

Nausea and vomiting of pregnancy (NVP)  is common and  usually settles by 12-14 weeks of pregnancy (although it may be longer and even last the full pregnancy). Often known as morning sickness it can occur at any time of the day or last all day.

Hyperemesis gravidarum is a severe form and can affect up to 1 to 3 in 100 pregnant women. Sadly, some women experience such extreme symptoms that they feel that they have no choice but to terminate the pregnancy even if it is a much longed for baby.

“I ended in termination of pregnancy after first hospital visit as I didn’t want to take from my child who was already here and after how badly I dealt with it last time, it being worse instantly I couldn’t do it”

Others decide that one child is sufficient to complete their family as they cannot contemplate symptoms again. There are medications but often primary care professionals do not appreciate the severity of symptoms or impact on mothers.

“I had HG with my daughter who will be 11 next month. Hyperemesis is the primary reason I only have one child. It was physically horrendous, and I had post-traumatic stress for years afterwards”.

“I had this with my daughter. It is the reason she will be an only child. She’s 4 now and I still suffer a lot of health issues as a direct result of hyperemesis. I had the best medical care. And was lucky to be given a  lot of treatment. But it wasn’t enough, and my body still struggled. You can’t appreciate how difficult it is until you’ve experienced it.”

When asked in a facebook group (https://www.facebook.com/breastfeedingandmedication) for their experiences of suffering from morning sickness and hyperemesis, one of the overwhelming comments from women was about reluctance of GPs to prescribe medication in pregnancy, even when it had been prescribed whilst the mother was hospitalised!

“After one of my hospitalisations I was sent home with a prescription for cyclizine and when I went to my GP to renew the prescription she talked me out of it because “it wasn’t making enough of a difference for me to go back to work” so didn’t seem worth taking (mild relief from the symptoms of HG wasn’t considered a benefit.)”

Repeated comments from family, friends and professionals underestimated how the woman was feeling and she didn’t feel listened to.

“I didn’t feel I wasn’t listened to and also I didn’t feel dismissed. I just accepted this was part and parcel of my pregnancy as it was just relayed to me that it was normal.”

“It was awful. People (friends, family, healthcare workers) were quick to tell me what worked for them, and I felt very blamed that I was somehow not trying hard enough. All the admissions were almost a relief, just to lie there with fluid going in. I used to be admitted for several days each week, particularly in third trimester. I still have consequences from the prolonged malnutrition.”

For what should be a joyous family time there were repeated descriptions of an awful experience:

“ horrendous, hell on earth,  pure hell, absolutely hell, housebound for months, nothing worked”.

“ I wasn’t taken seriously until my organs started to shut down and I needed to be induced, I spent 5 months in bed, couldn’t drink water or anything else, everything made me feel nauseous.”

“ I vomited so much and so hard that every time I wet myself and my nose bled. I was told when I was 5 weeks pregnant that if I didn’t want to be sick I shouldn’t be pregnant. I ended up hospitalized at 8 weeks.”

Should this be the experience of women in the UK in 2023?

Anti emetics in breastfeeding and pregnancy

Many of the drugs used to relieve nausea in pregnancy may be associated with lowering of milk supply. However, most women find that their supply very rapidly diminishes when they are pregnant. Many also develop aversion and very sensitive nipples and wish to limit feeding. Sadly, toddler nurslings don’t always understand the loss of their comfort! Many breastfeeding dyads continue to dry nurse throughout pregnancy and may go on to tandem feed. It is the decision which works for each family which matters, without judgement from family and professionals.

Hyperemesis may result in dehydration and subsequent admission to hospital.  Signs of dehydration include  feeling very thirsty, becoming drowsy or unwell, urine changing from a light yellow to a dark yellow or brown colour. Medical help should be sought if even sips of fluid produce vomiting. Weight loss can be excessive because of the restriction of quantity of food tolerated. Hyperemesis is diagnosed when there is prolonged nausea and vomiting  with more than 5% pre pregnancy weight loss, dehydration and electrolyte imbalance. https://cks.nice.org.uk/topics/nausea-vomiting-in-pregnancy/background-information/definition/

Self-care

https://cks.nice.org.uk/topics/nausea-vomiting-in-pregnancy/management/management/

• Rest as needed and try to avoid sensory stimuli that may trigger symptoms, such as odours, heat, and noise.
• Try eating plain biscuits or crackers in the morning.
• Try eating bland, small, frequent protein-rich meals which are low in carbohydrate and fat.
• Cold meals may be more easily tolerated if nausea is smell-related.
• Drinking little and often, rather than large amounts.
• Ginger (can be taken in fresh, tea, capsule, or syrup form).
• Acupressure (such as over the P6 point on the ventral aspect of the wrist using a wrist band or finger pressure).

Responses on the facebook group as to how helpful these suggestions were are exemplified by:

“Nausea and sickness with my first born I had such a heightened sense of smell. I couldn’t even open my fridge without feeling sick and running to the loo. I ended up using a cool bag instead of my fridge, and I had to call my mum to come and help me when my partner was away. I couldn’t brush my teeth without gagging and wanting to be sick.”

“I was asked what is had to eat and when I said an oat/raisin bar the doctor replied I shouldn’t be having anything sugary. That one doctor who knew her stuff had told me to eat anything I could keep down.”

Medical Treatment

The RCOG green top guidelines on treating are available https://www.rcog.org.uk/media/y3fen1x1/gtg69-hyperemesis.pdf

The UKTIS information on the use of drugs in pregnancy can be found at https://www.medicinesinpregnancy.org/Medicine–pregnancy/NV/

RCOG Recommended antiemetic therapies and dosages

In this fact sheet I have provided links to detailed information on the medication which can help prescribers to reach an evidence-based decision on the safety of the drug to the breastfeeding baby which is not available in standard reference texts like the British National Formulary (BNF). The linked pdf files contain information sourced from LACTMED February 2023

First Line treatments

• Cyclizine (Valoid™)

May possibly cause some drowsiness in the nursling but anecdotally appears to happen rarely . See https://www.ncbi.nlm.nih.gov/books/NBK501749/ and https://www.e-lactancia.org/breastfeeding/cyclizine/product/

Cyclizine is an anti-emetic used to treat nausea and vomiting including motion sickness, post-operative nausea and vomiting, after radiotherapy, in drug-induced situations, as well as for nausea in pregnancy. There are no reports of levels entering breastmilk (BNF) or data on which to base conclusions. There is an unlicenced dose for children aged over 6 years. It may be given orally, by IV or IM every 8 hours. Manufacturers advise to avoid in pregnancy, but there is no evidence of teratogenicity

· 

    

Prochlorperazine (Buccastem, Stemetil)

Low levels of prochlorperazine are secreted into breastmilk and it can be used when breastfeeding. Side effects for the mother include drowsiness, restlessness and occasional extra pyramidal effects but babies seem to exhibit no adverse reactions. It is licensed to be given directly to babies weighing more than 10 kg. See https://www.ncbi.nlm.nih.gov/books/NBK501080/ and https://www.e-lactancia.org/breastfeeding/prochlorperazine/product/

Prochlorperazine is used to treat vertigo, labyrinthitis, migraine or drug-induced emesis if severe vomiting is a problem. Its oral bio-availability is low due to high first-pass metabolism but, like all phenothiazines, it has many metabolites, some active. It is not generally used in travel sickness prophylaxis. It is a member of the phenothiazine family to which children are particularly sensitive. Long-term use should be avoided in breastfeeding where possible, particularly with very young babies where there is a potential risk of apnoea. However, short-term acute use probably poses few risks as it is licenced for use in children over 10 kg. The dose is 5-10mg (one or two tablets) every 6-8 hours. It may also be given IV or IM.

• Promethazine (Avomine™ Phenergan™, Sominex™)

 When used for hyperemesis in mother promethazine may possibly cause some drowsiness in the nursling but anecdotally appears to happen rarely. It also causes drowsiness in the mother so care should be taken with co sleeping.

See https://www.ncbi.nlm.nih.gov/books/NBK501081/ and https://www.e-lactancia.org/breastfeeding/promethazine/product/

Promethazine is widely used to reduce nausea particularly associated with travel sickness as well as symptomatic relief of urticaria and as an over-the-counter (OTC) hypnotic for short-term use. No data are available on transfer into breastmilk but it is believed that it does pass into breastmilk. It is licenced for use in children over 2 years.”

·        Doxylamine/pyridoxine (Xonvea™)

This is the only licensed drug treatment for nausea and vomiting of pregnancy. It contains a combination of the antihistamine doxylamine and the vitamin pyridoxine. It became available in England in 2018. It has been widely used for pregnancy sickness in the US and Canada and studies have shown no link with birth defects in the baby. The antihistamine doxylamine might be more likely to cause drowsiness in nursling. https://www.ncbi.nlm.nih.gov/books/NBK500620/  and https://www.e-lactancia.org/breastfeeding/doxylamine-succinate/product/. The 10mg pf pyridoxine is unlikely to cause any disruption to breastfeed.

Second Line Treatments

·        Metoclopramide (Maxolon™)

Metoclopramide has also been used to increase milk supply. It is associated with an increased risk of depression as well as other side effects if used long term. There are no reports of problems in the babies from the amount passing through breastmilk. https://www.ncbi.nlm.nih.gov/books/NBK501352/

Metoclopramide is a dopamine antagonist and can cause extra-pyramidal side effects, in particular acute dystonia. This adverse effect is most commonly seen in children and young adults, especially females, so it is not a drug of choice in lactating mothers who generally fall into this age group. It may also precipitate hypotension and depression. Other side effects reported include headache, diarrhoea, dry mouth and change in appetite (Ingram et al. 2011). It stimulates prolactin secretion and has been used as a galactogogue but has now been superseded by domperidone because of the latter does not cross the blood–brain barrier (Ingram et al. 2012). The bio-availability of oral metoclopramide is about 75% but varies widely between patients due to its hepatic first-pass metabolism. Concentrations higher than those in maternal plasma may be reached in breastmilk, particularly in the early puerperium, although these decrease with increased maturity. Metoclopramide has pro-kinetic and anti-emetic properties and acts directly on the gastrointestinal tract without altering acid secretion. It is more frequently used in the US where domperidone is not available. Relative infant dose is quoted as 4.7–14.3% (Hale  online access). The BNF states that only a small amount is present in breastmilk but it should be avoided.

·        Domperidone (Motilium™)

Domperidone has widely been used to increase milk supply in the past. Concerns were raised by the MHRA in 2014 about use in patients with heart defects, there has been some reticence by doctors to prescribe it. There are no reports of problems in the amounts passing through breastmilk

See https://www.ncbi.nlm.nih.gov/books/NBK501371/  and https://www.e-lactancia.org/breastfeeding/domperidone/product/

Domperidone acts at the chemoreceptor trigger zone. It stimulates gastric emptying. It causes fewer central effects such as sedation and dystonia (although there are still reports of these) because it does not cross the blood–brain barrier as metoclopramide does. Its dopamine antagonist activity stimulates prolactin release, which makes it useful as a galactagogue (see section on drugs to increase lactation, pages 285–288). Domperidone is metabolised by cytochrome P450 so care should be taken with potential interactions. It is more than 90% bound to plasma proteins and has a low bioavailability on an empty stomach (15%) when taking orally due to first-pass hepatic and intestinal metabolism. Mean serum levels of domperidone measured in babies through maternal use of 10 mg three times daily was only 1.2 ng per millilitre. The total amount of the drug that would be ingested by the infant (Da Silva et al. 2001) would be extremely small (about 180 ng per kilogramme daily, assuming a daily milk intake of 150 ml per kilogramme). Relative infant dose quoted as 0.01– 0.04% (Hale 2017 online access). The BNF states that the amount secreted into breastmilk is probably too small to be harmful.

·        Ondansetron  (Zofran™)

This is an anti-emetic originally used to treat people who have severe sickness when being treated with chemotherapy for cancer. Ondansetron is frequently used for nausea during and after caesarean section, usually in doses of 4 to 8 mg intravenously. Use during and after caesarean section appears to not affect the onset of breastfeeding. No adverse infant effects have been reported or among women who received ondansetron postpartum in a pharmacokinetic study. Use of ondansetron in nursing mothers beyond the immediate postpartum setting has not been studied well, but the drug is licensed for use in infants as young as 1 month of age. See https://www.ncbi.nlm.nih.gov/books/NBK500798/ and https://www.e-lactancia.org/breastfeeding/ondansetron/product/

This drug is a 5-HT3 antagonist with antiemetic activity. It is also for the prevention and treatment of post-operative nausea and vomiting that have not responded to other antiemetic agents. Ondansetron may also be used for nausea in pregnancy. It is licenced for use in children It is 60% orally bio-available and 70–75% plasma protein bound. The terminal half-life is three hours after oral doses. There are no studies on transfer into breastmilk although it has been found in animal studies (BNF).

A large, well-designed study found that the vast majority of babies exposed to ondansetron in the womb (at least 998 out of every 1,000) are born without cleft lip and/or palate (https://www.medicinesinpregnancy.org/Medicine–pregnancy/Morning-Sickness/)

Third Line

 Corticosteroids

Corticosteroids are sometimes prescribed for women with hyperemesis gravidarum that has not responded to other treatments including rehydration together with anti-emetics. There is no strong evidence that use of corticosteroids in early pregnancy increases the chance of cleft lip and palate or heart defects in the baby. Use in pregnancy also does not appear to increase the chance of the baby having a low birth weight. Some studies have shown that pregnant women taking corticosteroids have a higher chance of preterm delivery. However, it is thought that this is likely caused by the underlying illnesses that steroids are commonly used to treat rather than a direct effect of steroids themselves. https://www.medicinesinpregnancy.org/Medicine–pregnancy/Corticosteroids—systemic/

Pregnancy Sickness Support in the UK found that many women seeking terminations in desperation had not been offered the full range of treatments available and fewer than 10% had been offered steroids

Other non-medical treatments

·        Ginger

The conclusion from 6 randomised controlled trials with a total of 675 participants was that ginger extract at 1000 mgs per day may be effective treatment for NVP. However , the small number of patients in these studies allocated to receive ginger (n=303) may have been insufficient to properly test the safety of ginger with regards to pregnancy outcome. ( Viljoen, E., Visser, J., Koen, N. et al. A systematic review and meta-analysis of the effect and safety of ginger in the treatment of pregnancy-associated nausea and vomiting. Nutr J 13, 20 (2014).)  The authors found that Ginger did not significantly reduce the number of vomiting episodes during NVP, when compared to placebo, although there was a trend towards improvement. Many mothers have reported feeling angry and frustrated that this is recommended so frequently but that they found it caused side effects as well as not being effective. It is definitely not the answer to all NVP!

·        Acupressure

Stimulation of the acupressure point, located three fingers breadth above the wrist, has been used for many years to treat nausea from a variety of causes. Mohd Nafiah et al (2022)  concluded that the  use of acupressure wristbands at the P6 point was also able to decrease the frequency of antiemetics and increase the rate of urine ketone clearance. The implication of the  trial was the reported as the existence of an effective adjunct to alleviate the severity of nausea and vomiting in pregnant women with hyperemesis gravidarum, thereby improving their quality of life. There are no concerns about the safety of acupressure in pregnancy ( Mohd Nafiah, N.A.; Chieng, W.K.; Zainuddin, A.A.; Chew, K.T.; Kalok, A.; Abu, M.A.; Ng, B.K.; Mohamed Ismail, N.A.; Nur Azurah, A.G. Effect of Acupressure at P6 on Nausea and Vomiting in Women with Hyperemesis Gravidarum: A Randomized Controlled Trial. Int. J. Environ. Res. Public Health 2022, 19, 10886.)

Conclusion

We should not underestimate how NVP and HG affect pregnant women. We should listen to how they are feeling and ask how we can help. Untreated symptoms can lead to lifetime mental health issues.

“I had morning sickness (not hyperemesis). The first 4 months I went from bed to the sofa, my husband did everything. I couldn’t look at food, walk into the kitchen to get a drink etc. I wasn’t physically that sick but the nausea was absolutely horrendous. Constantly, nothing stopping it, the minute I woke to the second I fell asleep for 4 months. I lost 6kg by my first scan. Although it got better I still felt slightly sick through the whole pregnancy. I was refused anti nausea meds by multiple doctors, even the midwife shrugged it off. The effect it has had on me even now (my daughter is 2.5) is horrible. I still can’t eat certain foods, put too much food in my mouth and the slightest nausea (which I get often due to anxiety, migraines etc) sends me into complete panic.”

“What would you like professionals to understand? The struggle and how debilitating it is.”

“Medically, only one doctor seemed to have any awareness of what I was suffering from. Others told me “I’d be better in a couple of weeks” every two weeks.”

Resources

Pregnancy Sickness Support https://www.pregnancysicknesssupport.org.uk/

RCOG Green Top Guidelines https://www.rcog.org.uk/guidance/browse-all-guidance/green-top-guidelines/the-management-of-nausea-and-vomiting-of-pregnancy-and-hyperemesis-gravidarum-green-top-guideline-no-69/

UKTIS Medicines in Pregnancy https://www.medicinesinpregnancy.org/About-Us/

After some discussions with the Thyroid Trust I have put this information together

PDF of this factsheet available here https://breastfeeding-and-medication.co.uk/wp-content/uploads/2023/02/thyroid-and-breastfeeding-.pdf

Underactive Thyroid and Breastfeeding (Hypothyroid)

“Many medical professionals seem unaware of how important adjusting meds during and post pregnancy is and that it can influence breastfeeding as well”

Description

An underactive thyroid gland is where the thyroid gland does not produce enough hormones. Common signs of an underactive thyroid are :

• tiredness,
• weight gain
• feeling depressed
• being sensitive to the cold,
• slowed thought processes,
• muscle pains
• dry skin and brittle hair.

Most people presenting with symptoms of depression will be asked to have a blood test before medical treatment. Similarly although it is normal to lose the thicker hair which is enjoyed in pregnancy, significant hair loss should also be considered a possible symptom.

Hypothyroidism is identified by blood tests which are conducted regularly until they are within stabilised levels. Blood levels are ideally taken routinely after delivery and especially  if the mother reports a poor milk supply. Levels at the low end of normal are frequently associated with low prolactin and poor breastmilk supply.

Hypothyroidism is ten times more common in women than it is in men. In the UK, around 1-2 in 100 people have hypothyroidism. It most commonly develops in adult women and becomes more common with increasing age. However, it can occur at any age and can affect anyone.

Treatment

Levothyroxine is secreted in extremely low levels into breastmilk, if at all (Bennett 1988; Oberkotter 1983; Sato 1979). It is highly bound to proteins in the maternal plasma, so little is free to pass into breastmilk.

The level to which the baby will be exposed via breastmilk is virtually undetectable. Levels secreted into milk are too low to influence tests for neonatal hypothyroidism according to Martindale (2017). There is no need to routinely test breastfed babies unless there They should be swallowed with water on an empty stomach, with no food for 30 minutes afterwards.

References

• Bennett PN (ed.), Drugs and Human Lactation, Amsterdam: Elsevier, 1988.
• Brown A Jones W A guide to breastfeeding for the medical professional Routledge 2019
• Drugs and Lactation Database (LactMed®) https://www.ncbi.nlm.nih.gov/books/NBK501003/
• E lactancia https://www.e-lactancia.org/breastfeeding/levothyroxine/product/
• Jones W Breastfeeding and Medication Routledge 2018
• Martindale The Complete Drug Reference. Pharmaceutical Press 2017
• Oberkotter LV, Tenore A, Separation and radioimmunoassay of T3 and T4 in human breastmilk, Horm Res, 1983;17:11–18.
• Sato T, Suzuki Y, Presence of triiodothyronine, no detectable thyroxine and reverse triiodothyronine in human milk, Endocrinol Jpn, 1979;26:507–13.

Overactive thyroid and breastfeeding  (Hyperthyroid disease)

“I was told to stop breast feeding immediately after being put on carbimazole for an overactive thyroid. I’m still so angry that it wasn’t necessary”

Description

Hyperthyroidism has a variety of causes. It is ten times more common in women than men, and typically begins between 20 and 40 years of age It is often diagnosed post-partum in breastfeeding women.

Symptoms include:

• nervousness,
• anxiety and irritability,
• mood swings,
• difficulty sleeping,
• persistent tiredness and weakness,
• sensitivity to heat, palpitations,
• weight loss (despite increased appetite),

Three in every 4 cases of hyperthyroid are caused by Graves’ disease, an auto-immune condition.  Less commonly it develops because of nodules on the thyroid gland.

Treatment

Carbimazole – is a pro-drug that is bioactivated to methimazole. It produces sub-clinical levels in infants exposed to less than 30 mg a day through their mother’s breastmilk (Rylance 1987). Carbimazole has a relative infant dose of 2.3% – 5.3% (Hale) where levels less than 10% are regarded as compatible with breastfeeding.

In a study of 5 five lactating women receiving 40 mg/d, the mean concentration of methimazole in milk measured by .Johansen was 182 µg/L, with a mean milk/serum ratio of 0.98.  The mean total amount of methimazole excreted in milk over 8 h was 34 µg. The limited data suggest that the transfer of carbimazole is too low to affect thyroid function in breastfeeding infants.

If the drug is used at a dose above 30mg, monitoring of the infant’s thyroid function periodically might be advisable. Otherwise monitoring would only be necessary if the baby exhibits clinical symptoms.

In February 2019 the MHRA issued a notice that “ Carbimazole is associated with an increased risk of congenital malformations, especially when administered in the first trimester of pregnancy and at high doses. Women of childbearing potential should use effective contraception during treatment with carbimazole.”  https://breastfeeding-and-medication.co.uk/fact-sheet/carbimazole-in-women-of-childbearing-age

References

• Brown A Jones W A guide to breastfeeding for the medical professional Routledge 2019
• Drugs and Lactation Database (LactMed®) https://www.ncbi.nlm.nih.gov/books/NBK501759/
• E lactancia https://www.e-lactancia.org/breastfeeding/carbimazole/product/
• Hale TW  and Krutsch K Hale’s Medications & Mothers’ Milk™ 2023: A Manual of Lactational Pharmacology (also available as https://www.halesmeds.com/ by subscription). Springer Pub
• Jones W Breastfeeding and Medication Routledge 2018
• MHRA Carbimazole: increased risk of congenital malformations; strengthened advice on contraception www.gov.uk/drug-safety-update/carbimazole-increased-risk-of-congenital-malformations-strengthened-advice-on-contraception
• Rylance GW, Woods CG, Donnelly MC, Oliver JS, Alexander WD, Carbimazole and breastfeeding, The Lancet, 1987;1(8538):928

Propylthiouracil has been the drug of choice in a breastfeeding mother as the transfer into breastmilk is lower than that with carbimazole. In 2009 the US Food and Drug Administration (FDA) in the USA alerted practitioners to an increased risk of hepatotoxicity (liver toxicity)  with PTU use and recommended that all patients should be observed and monitored for signs of liver disease, particularly during the first six months of treatment. Signs of liver damage, which should be reported to the prescriber immediately are anorexia, nausea, vomiting, fatigue, abdominal pain, jaundice, dark urine, or pruritus (BNF). Propylthiouracil crosses the placenta and in high doses may cause foetal goitre and hypothyroidism.

Only small amounts of propylthiouracil are secreted into breastmilk and reports suggest that levels are too low to produce side effects (Cooper 1987). Propylthiouracil is extensively plasma protein bound (80%) and has an oral bioavailability of 50–75% which is low. At doses of 400 mg, a study of nine women and their babies showed levels of PTU in milk reached only 0.7 µg per millilitre (Kampmann 1980). One of the babies was studied for five months during which the mother received 200–300 mg of PTU daily. There were no changes to the infant’s thyroid functions. Momotani’s (2000) study of 11 babies has shown that up to 750 mg produced no changes in babies monitored up until 11 months of age. Monitoring is recommended as a precaution if clinical symptoms are identified in the baby.

References

• Cooper DS, Antithyroid drugs: to breastfeed or not to breastfeed, Am J Obstet Gynecol, 1987;157:234–5.
• Drugs and Lactation Database (LactMed®) https://www.ncbi.nlm.nih.gov/books/NBK501084/
• E lactancia https://www.e-lactancia.org/breastfeeding/propylthiouracil-ptu/product/
• FDA Alert 2009, Information for Healthcare Professionals – Propylthiouracil-Induced Liver Failure (www.fda.gov/Drugs/DrugSafety/PostmarketDrugSafetyInformationforPatientsandProviders/DrugSafetyInformationforHeathcareProfessionals/ucm162701.htme).
• Hale TW  and Krutsch K Hale’s Medications & Mothers’ Milk™ 2023: A Manual of Lactational Pharmacology (also available as https://www.halesmeds.com/ by subscription). Springer Pub
• Jones W Breastfeeding and Medication Routledge 2018
• Kampmann JP, Johansen K, Hansen JM, Helweg J, Propylthiouracil in human milk, The Lancet,1980;1(8171):736–7.
• Momotani N, Yamashita R, Makino F, Noh JY, Ishikawa N, Ito K, Thyroid function in wholly breastfeeding infants whose mothers take high doses of propylthiouracil, Clin Endocrinol (Oxf), 2000;53(2):177–81.

Propranolol is often used to relieve symptoms of an over active thyroid. It is 90% plasma protein bound, the milk plasma ratio and it is only 30% orally bio available. Its relative infant dose is 0.3-0.5% so virtually none passes into milk and breastfeeding can continue as normal. This has been confirmed in several studies.

References

• Bauer JH, Pape B, Zajicek J, Groshong T. Propranolol in human plasma and breast milk. Am J Cardiol. 1979; 43(4):860-862.
• Brown A Jones W A guide to breastfeeding for the medical professional Routledge 2019
• Drugs and Lactation Database (LactMed®) https://www.ncbi.nlm.nih.gov/books/NBK501162/
• Elactancia https://www.e-lactancia.org/breastfeeding/propranolol/product/
• Hale TW  and Krutsch K Hale’s Medications & Mothers’ Milk™ 2023: A Manual of Lactational Pharmacology (also available as https://www.halesmeds.com/ by subscription). Springer Pub
• Jones W Breastfeeding and Medication Routledge 2018
• Lewis AM, Patel L, Johnston A, Turner P. Mexiletine in human blood and breast milk. Postgrad Med J. 1981 Sep;57(671):546-547.
• Smith MT, Livingstone I, Hooper WD, Eadie MJ, Triggs EJ. Propranolol, propranolol glucuronide, and naphthoxylactic acid in breast milk and plasma. Ther Drug Monit. 1983; 5(1):87-93.
• Taylor EA, Turner P. Anti-hypertensive therapy with propranolol during pregnancy and lactation. Postgrad Med J. 1981;57(669):427-430.

Radiotherapy involving ingestion of iodine is not suitable during breastfeeding as iodine concentrates in breastmilk and lasts for some time so would mean stopping breastfeeding