Is Tamiflu (Oseltamivir) safe during pregnancy?

From the Guidelines

Tamiflu (Oseltamivir) is considered safe for use during pregnancy, and its benefits outweigh the risks, especially for pregnant women with confirmed or suspected influenza, as stated in the 2011 guidelines from the Advisory Committee on Immunization Practices 1. The use of Tamiflu during pregnancy is recommended due to the higher risk of complications from influenza in pregnant women, which can be more severe than the potential side effects of the medication.

• The standard adult dose of 75 mg twice daily for 5 days for treatment, or 75 mg once daily for prevention, is also recommended for pregnant women, with treatment ideally starting within 48 hours of symptom onset for maximum effectiveness.
• According to the guidelines, pregnancy should not be considered a contraindication to oseltamivir use, and reducing fever with acetaminophen or antiviral medications like Tamiflu may reduce the risk of adverse fetal outcomes 1.
• While Tamiflu is classified as a "Pregnancy Category C" medication, indicating inadequate data on its safety for pregnant women, a retrospective cohort study found no evidence of an association between oseltamivir use during pregnancy and adverse events such as preterm birth, premature rupture of membranes, or malformations 1.
• As with any medication during pregnancy, Tamiflu should be used under a healthcare provider's guidance, considering individual circumstances and risk factors, to minimize potential risks and maximize benefits.

From the FDA Drug Label

8. 1 Pregnancy

Risk Summary There are no adequate and well-controlled studies with oseltamivir phosphate for oral suspension in pregnant women to inform a drug-associated risk of adverse developmental outcomes. Available published epidemiological data suggest that oseltamivir phosphate for oral suspension, taken in any trimester, is not associated with an increased risk of birth defects However, these studies individually are limited by small sample sizes, use of different comparison groups, and some lacked information on dose, which preclude a definitive assessment of the risk

The FDA drug label does not provide conclusive evidence to confirm the safety of Tamiflu (Oseltamivir) during pregnancy, but available data suggest it is not associated with an increased risk of birth defects. Pregnancy risk cannot be definitively assessed due to limitations in the studies.

• Key points: + No adequate and well-controlled studies in pregnant women + Epidemiological data suggest no increased risk of birth defects + Studies are limited by small sample sizes and lack of dose information 2

From the Research

Safety of Tamiflu (Oseltamivir) during Pregnancy

• The use of oseltamivir for the treatment of influenza during pregnancy is recommended by several studies 3, 4, 5, 6, 7.
• Oseltamivir has been shown to prevent disease among exposed individuals, shorten the duration of illness, and lessen the likelihood of complications among those infected 4, 5.
• The American College of Obstetricians and Gynecologists (ACOG) recommends that pregnant women with suspected or confirmed influenza receive antiviral treatment with oseltamivir or zanamivir based on current resistance patterns 3.
• Treatment with oseltamivir within 48 hours of the onset of symptoms is ideal, but treatment should not be withheld if the ideal window is missed 3, 6.
• The safety profiles of antiviral drugs during pregnancy are limited, but available risk-benefit evidence indicates that pregnant women with suspected or confirmed influenza should receive prompt antiviral therapy to reduce the risk of complications and attenuate the teratogenic effects of the influenza infection 7.
• There is no evidence of adverse fetal outcomes as a result of most in utero exposures to neuraminidase inhibitors, including oseltamivir 7.

Benefits of Oseltamivir during Pregnancy

• Oseltamivir has been demonstrated to decrease morbidity and mortality when given within 48 hours of symptom onset 6.
• Early oseltamivir treatment, along with maternal vaccination, can mitigate the risks of worse maternal, obstetric, and neonatal outcomes associated with influenza during pregnancy 6.
• Oseltamivir can prevent disease after exposure, treat infected individuals, and lessen the likelihood of complications 4, 5.

Considerations for Oseltamivir Use during Pregnancy

• The physiologic adaptations of pregnancy may alter the pharmacokinetics and pharmacodynamics of oseltamivir 4, 5.
• Large, population-based studies are needed to assess the association between in utero oseltamivir exposure and fetal outcome 7.
• Post-exposure prophylaxis with oseltamivir may be prescribed in pandemic settings, particularly to non-vaccinated women 7.