Oral oseltamivir (sold as Tamiflu) is the preferred antiviral for treating influenza during pregnancy, backed by the most safety data of any flu medication in this population. For symptom relief, acetaminophen (Tylenol) remains the safest over-the-counter pain reliever and fever reducer available to pregnant women, though even it should be used at the lowest effective dose for the shortest time needed.
Pregnancy changes your immune system in ways that make the flu more dangerous than it would be otherwise. A CDC study published in The Lancet Infectious Diseases found that flu during pregnancy was linked to reduced birthweight in full-term newborns and a higher risk of pregnancy loss after 13 weeks. Women who developed fever with respiratory symptoms also faced increased odds of preterm birth. That’s why prompt treatment matters.
Antiviral Treatment: Oseltamivir Is First Choice
The CDC recommends oral oseltamivir as the go-to antiviral for pregnant women with suspected or confirmed flu. Multiple studies have confirmed its safe use during pregnancy, and it has the largest body of evidence supporting both its effectiveness and safety in this population. Treatment lasts five days, and starting within 48 hours of your first symptoms gives you the best chance of reducing severity and complications. The FDA echoes this: if your doctor prescribes an antiviral, don’t wait to begin taking it.
There is an inhaled antiviral called zanamivir (Relenza) that is also considered an option, though oseltamivir is generally preferred because it’s taken as a pill rather than inhaled. Your body processes drugs differently during pregnancy due to changes in kidney function, so your doctor may adjust the dose accordingly.
One antiviral to be aware of: baloxavir (Xofluza), a newer single-dose flu treatment, is not recommended during pregnancy or breastfeeding. There simply isn’t enough safety or efficacy data for it in pregnant women, and the CDC explicitly advises against its use in this group.
Acetaminophen for Fever and Body Aches
Acetaminophen is the safest over-the-counter option for managing flu-related fever and pain during pregnancy. That said, the FDA has issued guidance urging doctors and patients to minimize its use, particularly for routine low-grade fevers. Some studies have described an association between chronic acetaminophen use throughout pregnancy and a slightly higher risk of neurological conditions like autism and ADHD in children, though a direct cause-and-effect relationship hasn’t been established.
The practical takeaway: use acetaminophen when you genuinely need it for a high or persistent fever, but don’t take it around the clock for mild discomfort. Most short-term fevers in pregnant women don’t require medication at all. When you do use it, stick to the lowest dose that helps and stop when your symptoms improve.
Pain Relievers to Avoid
NSAIDs, the class of drugs that includes ibuprofen (Advil, Motrin), naproxen (Aleve), and aspirin, carry specific risks during pregnancy. The FDA warns against using any NSAID from 20 weeks of pregnancy onward because these drugs can cause kidney problems in the developing baby. Since the baby’s kidneys produce most of the amniotic fluid after 20 weeks, impaired kidney function can lead to dangerously low fluid levels. Amniotic fluid cushions the baby and is essential for lung, digestive, and muscle development.
At around 30 weeks, NSAIDs pose an additional threat: premature closure of a blood vessel in the baby’s heart called the ductus arteriosus, which can lead to serious cardiac complications. Even in the first trimester, acetaminophen is considered safer than NSAIDs for treating flu symptoms.
Cough Suppressants and Expectorants
Dextromethorphan, the active ingredient in many over-the-counter cough medicines (Robitussin DM, Delsym), is not expected to increase the chance of birth defects. A study of 128 women who took it during the first trimester found no increased risk of miscarriage, and a separate study of 184 women who used it at various points in pregnancy found no higher rates of stillbirth or low birthweight.
Guaifenesin, the expectorant found in Mucinex, is used to thin mucus and make coughing more productive. Most available evidence suggests it does not significantly increase the risk of birth defects, though the data is more limited than for some other medications.
Two important rules apply to both:
- Choose single-ingredient products. Combination cold medicines bundle multiple active ingredients together, and some of those ingredients may not be safe during pregnancy. Pick a product that targets only the symptom you’re treating.
- Avoid liquid formulas containing alcohol. Some cough syrups use alcohol as a solvent. Check the label and choose an alcohol-free version.
The Flu Vaccine as Prevention
Getting a flu shot during pregnancy does double duty. It protects you during a time when your immune system is more vulnerable, and it passes protective antibodies to your baby through the placenta. This passive immunity is especially valuable because flu vaccines aren’t approved for infants under six months old, leaving newborns in a gap period where they’re highly susceptible to infection.
Research in Clinical and Experimental Immunology found that maternal vaccination significantly boosted antibody levels in both mother and baby at the time of birth, with protection lasting in infants up to two to three months at measurable blood levels and reducing the risk of infection for up to six months. Depending on the study, vaccinated mothers saw a 45 to 63 percent reduction in confirmed flu cases among their newborns and young infants. Antibody transfer through the placenta is most efficient in the third trimester, but vaccination at any point during pregnancy provides benefit.
Quick Reference: What’s Safe and What’s Not
- Oseltamivir (Tamiflu): Preferred antiviral, start within 48 hours of symptoms, 5-day course
- Zanamivir (Relenza): Alternative antiviral option (inhaled)
- Acetaminophen (Tylenol): Safest OTC pain/fever reliever, use lowest effective dose
- Dextromethorphan: Cough suppressant, no expected increase in birth defect risk
- Guaifenesin: Expectorant, most evidence suggests low risk
- Baloxavir (Xofluza): Not recommended, no pregnancy safety data
- Ibuprofen, naproxen, aspirin (NSAIDs): Avoid, especially after 20 weeks