Paxlovid in Pregnancy & Breastfeeding: FDA Pregnancy Category, CDC Guidelines, Safety, Side Effects in Females

Content:

• What is Paxlovid in Pregnancy & Breastfeeding?
• Paxlovid in Pregnancy & Breastfeeding — FDA Pregnancy Category
• Paxlovid in Pregnancy & Breastfeeding — CDC Guidelines
• Paxlovid in Pregnancy & Breastfeeding — Safety
• Paxlovid in Pregnancy & Breastfeeding — Side Effects in Females

What is Paxlovid in Pregnancy & Breastfeeding?

Paxlovid is the oral antiviral combination of nirmatrelvir (a SARS-CoV-2 protease inhibitor) plus ritonavir (a pharmacokinetic booster). It is prescribed to reduce the risk of progression to severe COVID-19 in people at higher risk of complications when started early in the course of symptomatic infection. When we talk about “Paxlovid in pregnancy & breastfeeding,” we mean the clinical question of whether to offer this treatment to pregnant or lactating patients who meet criteria for antiviral therapy. Pregnancy and lactation raise two related concerns: first, whether the benefits of reducing COVID-19 complications for the pregnant person (and indirectly the fetus) outweigh unknown or theoretical risks of the drug exposure, and second, whether drug components pass into breastmilk and what that might mean for the infant. Key clinical societies and public health agencies have made practical recommendations acknowledging limited direct trial data in pregnancy but recognizing that the harms of untreated COVID-19 in pregnancy can be substantial, and they therefore favor offering effective antiviral therapy when indicated.

In practice, treating clinicians weigh individual risk: maternal age and comorbidities, gestational age, severity of symptoms, drug interactions (ritonavir has many), and patient preferences. Ritonavir has long experience in pregnancy as part of antiretroviral regimens for HIV, which helps inform safety expectations, while nirmatrelvir is newer and has far less pregnancy-specific data. Available observational data and expert guidance suggest that nirmatrelvir/ritonavir (Paxlovid) should not be withheld from pregnant people who otherwise qualify for therapy because the potential to prevent severe disease and preterm birth or other pregnancy complications often outweighs the limited theoretical drug risks. For breastfeeding, manufacturers and some advisors note that Paxlovid components may pass into breast milk and suggest discussing options and timing with lactation and prescribing teams; some guidance (and product labeling) advises caution and individualized counseling. 

Paxlovid in Pregnancy & Breastfeeding — FDA Pregnancy Category

The old FDA pregnancy letter categories (A, B, C, D, X) have been phased out in favor of the Pregnancy and Lactation Labeling Rule (PLLR), which requires narrative summaries of available data and clinical considerations rather than a single letter. For Paxlovid, the FDA product information states that data on nirmatrelvir in pregnancy are limited and insufficient to establish a clear risk profile for birth defects or miscarriage, and it therefore provides a factual risk summary and counseling points instead of a letter grade. The label highlights that ritonavir has substantial pregnancy experience from HIV treatment and that published observational studies have not identified a clear increase in major birth defects attributable to ritonavir itself. Because there are no large randomized trials of Paxlovid in pregnancy, the FDA and manufacturers direct clinicians to use risk-benefit judgment and to discuss uncertainties with patients. 

What that means for clinicians is practical: you will not see a single “category” on the Paxlovid label. Instead, the label's “Use in Specific Populations” section summarizes the limited human pregnancy data and the animal reproductive toxicity findings (if any), and it recommends that clinicians discuss potential risks and benefits. This narrative approach is intended to encourage individualized counseling—explaining what is known (ritonavir’s pregnancy safety experience, limited nirmatrelvir data), what is unknown (long-term outcomes, rare events), and the known risks of COVID-19 in pregnancy (for example, increased risk of ICU admission, oxygen requirement, and adverse obstetric outcomes) so that the pregnant person can make an informed decision. If you need a quick reference, the FDA fact sheets and professional guidance documents are the authoritative sources to quote during counseling.

Paxlovid in Pregnancy & Breastfeeding — CDC Guidelines

CDC clinical guidance for COVID-19 treatment in special populations emphasizes that pregnant and lactating people should not be routinely excluded from receiving effective antiviral therapies when clinically indicated. The CDC notes that treatment decisions should be made jointly by the patient and clinician, considering both maternal benefits and potential fetal or neonatal risks. For ambulatory patients at high risk of progression, CDC lists ritonavir-boosted nirmatrelvir as an appropriate outpatient option and explicitly states that pregnancy should not be an automatic reason to withhold therapy. The Agency also refers clinicians to specialty society guidance (e.g., ACOG, NIH/IDSA) for detailed pregnancy-specific recommendations and dosing adjustments when required.

Several professional bodies (including ACOG and NIH) echo the CDC’s practical stance: because pregnant people face higher risks from COVID-19 and because effective outpatient antivirals reduce progression to severe illness, offering Paxlovid to eligible pregnant patients is reasonable after individualized counseling. For breastfeeding people, many UK and institutional sources recommend continuing breastfeeding during COVID-19 illness even if antiviral therapy is given, while counseling on potential transfer into milk and timing may vary. Clinicians should also be careful to review drug–drug interactions and renal dosing, which may influence the choice or dose of Paxlovid in pregnancy. Overall, the public health and specialty guidance landscape has shifted toward not denying evidence-based antivirals to pregnant and lactating patients when the expected benefit outweighs uncertain risk.

Paxlovid in Pregnancy & Breastfeeding — Safety

Safety assessment combines known pharmacology, existing pregnancy experience with ritonavir, animal reproductive studies, and emerging human observational data. Ritonavir, used for decades in HIV regimens, has an overall reassuring safety record in pregnancy with large observational datasets and registry information; it has not been consistently associated with major teratogenic signals. Nirmatrelvir is newer, and human pregnancy exposure data remain limited; small observational series and case reports to date have not demonstrated a clear signal for major congenital anomalies, but numbers are small and surveillance continues. Regulatory documents and teratology information services therefore conclude that available evidence does not identify a major fetal risk, but emphasize that definitive safety evidence (from randomized pregnancy trials) is lacking. Clinicians commonly rely on this pragmatic interpretation: the known maternal risks of untreated or progressive COVID-19 in pregnancy often outweigh the theoretical or poorly quantified drug risks.

For breastfeeding, studies and lactation databases (e.g., LactMed, MotherToBaby) indicate that ritonavir is detectable in breast milk but generally at low levels; nirmatrelvir transfer into breast milk appears to be limited based on small pharmacokinetic reports. A recent small study and expert reviews suggest low infant exposure through milk and no immediate acute safety signals in the limited follow-up available, but long-term data are sparse. Because both the maternal benefit of treating COVID-19 and the low measured milk exposures favor continuing breastfeeding in many situations, most guidance encourages individualized discussion rather than a blanket contraindication. Some product literature recommends considering temporary interruptions to breastfeeding or pumping and discarding milk during treatment in particular circumstances, but many professional groups (and the NHS in the UK) say breastfeeding may continue with appropriate counseling—again stressing shared decision-making.

Paxlovid in Pregnancy & Breastfeeding — Side Effects in Females

The side-effect profile of Paxlovid in pregnant and nonpregnant adults is similar, with the most commonly reported adverse effects being altered taste (dysgeusia), diarrhea, increased blood pressure, and myalgias. These side effects are generally mild to moderate and often self-limited after the five-day treatment course. In pregnancy, clinicians also monitor for obstetric-specific concerns—such as preterm labor signals, fluid status, and fetal monitoring as appropriate—because systemic illness or severe side effects could secondarily affect pregnancy. Importantly, ritonavir’s interaction profile can affect concomitant medications used in pregnancy (for example, some antiemetics, antihypertensives, or epilepsy drugs), necessitating a careful medication review before prescribing.

When counseling female patients who are pregnant or breastfeeding, it is useful to cover both common and rare risks: common transient effects (taste disturbance, GI upset) and rare but clinically important issues—renal dosing adjustments, significant drug–drug interactions that could affect maternal stability, and the very rare potential for hypersensitivity. Because cardiac and metabolic stress from COVID-19 itself can threaten pregnancy outcomes, preventing progression with an effective antiviral often reduces overall risk. Documented post-marketing surveillance continues, and clinicians should report pregnancy exposures to registries to improve the evidence base. In all cases, shared decision-making—discussing the patient’s values, the local prevalence and severity of COVID-19, and specific maternal comorbidities—remains the cornerstone of appropriate care.