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Flu (influenza) and Anti virals

I think we are all much more aware of the incidence of flu and its complications after the COVID pandemic. The best form of protection (although still not 100%) is flu vaccination which can be undertaken whilst breastfeeding with no risk to the baby. The symptoms of flu usually last for a week. Symptoms develop approximately 4 days after infection. Lateral flow tests should be used to differentiate between flu and covid.

Ways to try to avoid flu

  • Wash hands with soap and water regularly
  • regularly clean surfaces such as your computer keyboard, telephone and door handles to get rid of germs
  • Wash hands before eating or touching face – the virus can be spread from door handles and other surfaces
  • Try to avoid crowded venues if possible. Wearing a mask may offer protection

People with flu can spread it to others up to about 6 feet away. Most experts think that flu viruses are spread mainly by droplets made when people with flu cough, sneeze or talk. These droplets can land in the mouths or noses of people who are nearby or possibly be inhaled into the lungs. Less often, a person might also get flu by touching a surface or object that has flu virus on it and then touching their own mouth or nose.

Symptoms of flu include a sudden fever – a temperature of 38C or above, aching body, feeling tired or exhausted, dry or less frequently chesty cough, sore throat, headache, difficulty sleeping, loss of appetite, diarrhoea or tummy pain, nausea and being sick. You may feel too weak to get out of bed so need help to care for your baby/children. The symptoms are similar for children, but they can also get pain in their ear and appear less active. ( https://www.nhs.uk/conditions/flu/)

A cold develops more slowly and affects mainly the nose and throat. With ‘flu it is impossible to carry on with life as normal. Imagine if your favourite singer or actor knocked at your front door. If you have flu you wont care!

If you catch flu

•             Take regular paracetamol and ibuprofen

•             Keep drinking fluids

•             Rest as much as possible

•             Cover your nose and mouth with a tissue when you cough or sneeze. Throw the tissue in the bin after you use it.

There is usually no reason to consult a doctor if you are normally fit and well, unless the symptoms have persisted for more than 7 days or you have difficulty breathing. Antibiotics do not help the flu virus itself although may be necessary for secondary infections. You are at greater risk of complications if you are pregnant.

People at high risk may be prescribed antiviral medications to help reduce the symptoms of influenza. They must be taken within two days of the start of symptoms to be effective.

  • Oseltamivir (Tamiflu ®) – oral medication

Limited data indicate that oseltamivir and its active metabolite are poorly excreted into breastmilk. Maternal dosages of 150 mg daily produce low levels in milk and would not be expected to cause any adverse effects in breastfed infants, especially if the infant is older than 2 months (normal dose 75mg daily). Infants over 1 year of age can receive oseltamivir directly in doses much larger than those in breastmilk (Lactmed 2023, Wentges-van HN, van EM, van der Laan JW. Oseltamivir and breastfeeding. Int J Infect Dis. 2008).

  • Zanamivir (Relenza ®) – inhaled drug

No information is available on the use of zanamivir during breastfeeding. One group of authors estimated that an exclusively breastfed 5 kg infant would receive about 0.075 mg daily in breastmilk after an inhaled maternal dose of 10 mg, which is less than 1% of the dose in older children. In addition, because zanamivir is poorly absorbed orally, it is not likely to reach the bloodstream of the infant in clinically important amounts. ( LactMed 2023, Tanaka T, Nakajima K, Murashima A et al. Safety of neuraminidase inhibitors against novel influenza A (H1N1) in pregnant and breastfeeding women. CMAJ. 2009;181:55-8

The manufacturer reports that it is present in the milk of rodents although no human data are available. Due to the poor oral or inhaled absorption and the incredibly low plasma levels, it is unlikely to produce untoward effects in breastfed infants (Hale Medications & Mothers Milk 2023)

see also https://breastfeeding-and-medication.co.uk/fact-sheet/coughs-colds-flu-and-covid-when-breastfeeding

Mother and breastfed baby

  • The baby should not be separated from the mother unless she is too unwell to care for it. I Her breastmilk contains antibodies against flu which can protect the baby from more serious infection just as we saw with COVID infection.
  • Children under the age of 2 years are at greater risk of secondary infections and professional support should be sought. It is important that babies and children are monitored for symptoms of dehydration (dry nappies, sunken fontanel, lethargy).


  • F.O. Uruakpa, M.A.H. Ismond, E.N.T. Akobundu Colostrum and its benefits: a review. Nutrition Research 22 (2002) 755–767
  • https://www.cdc.gov/flu/
  • https://www.sps.nhs.uk/articles/using-oseltamivir-and-zanamivir-during-breastfeeding/
  • Schlaudecker EP, Steinhoff MC, Omer SB, McNeal MM, Roy E, Arifeen SE, et al. (2013) IgA and Neutralizing Antibodies to Influenza A Virus in Human Milk: A Randomized Trial of Antenatal Influenza Immunization. PLoS ONE 8(8): e70867. http://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0070867
  • Trend S de Jong E, Lloyd ML, Kok CH, Richmond P, Doherty DA, Simmer K, Kakulas F Strunk T, Currie A.Leukocyte Populations in Human Preterm and Term Breast Milk Identified by Multicolour Flow Cytometry . PLoS One. 2015 A http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0135580
  • Trend S, Strunk T, Lloyd ML, Kok CH, Metcalfe J, Geddes DT, Lai CT, Richmond P, Doherty DA, Simmer K, Currie A. Levels of innate immune factors in preterm and term mothers’ breast milk during the 1st month postpartum. Br J Nutr. 2016 Apr 14;115(7):1178-93

With thanks to Dr K.J Klottrup-Rees for her help with the biomedical science aspect of this information

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