Vardenafil (Levitra/Staxyn) Pregnancy and Lactation Safety

Why Vardenafil Has No Female or Obstetric Indication

Vardenafil (marketed as Levitra and Staxyn) received FDA approval in 2003 strictly for the treatment of erectile dysfunction in men. The drug was never studied in registration trials that enrolled women, pregnant individuals, or nursing mothers. Because erectile dysfunction is a male-specific condition, Bayer and GlaxoSmithKline designed every key trial, including the Porst et al. 2003 study of vardenafil in diabetic ED (N=452), around adult male populations 1.

The absence of a female indication is not incidental. PDE5 inhibitors as a class were developed to target penile hemodynamics, and regulatory agencies did not require sponsors to generate pregnancy or lactation data for an exclusively male-labeled product. The current FDA-approved prescribing information states that vardenafil "is not indicated for use in women" 2. That single sentence carries significant clinical weight: it means no dose, duration, or monitoring protocol has been validated for female patients in any reproductive state.

FDA Pregnancy Categorization and What It Means

Under the legacy FDA letter-category system (replaced by the Pregnancy and Lactation Labeling Rule, or PLLR, in 2015), vardenafil held a Category B rating. Category B indicates that animal reproduction studies failed to demonstrate fetal risk, but adequate and well-controlled studies in pregnant humans do not exist 3.

This distinction matters. Category B is not a safety endorsement. It tells clinicians only that rats and rabbits exposed to vardenafil during organogenesis did not produce offspring with structural malformations at tested doses. The Levitra prescribing information reports no teratogenicity at oral doses up to 18 mg/kg/day in rats and 6 mg/kg/day in rabbits, exposures roughly 29-fold and 11-fold the maximum recommended human dose (MRHD) of 20 mg based on AUC, respectively 2.

A high animal-to-human exposure margin is reassuring but not conclusive. Thalidomide, for example, showed minimal teratogenicity in certain rodent strains yet caused severe limb defects in humans. Animal data reduce uncertainty. They do not eliminate it.

Since June 2015, new drug labels no longer carry letter categories. Instead, the PLLR requires a narrative summary of available data, risk discussion, and clinical considerations 3. Because vardenafil labeling has not been updated with PLLR-format pregnancy subsections (given its male-only indication), clinicians referencing older labels will still encounter the Category B designation.

Animal Reproductive Toxicity Data

The preclinical reproductive toxicology package for vardenafil included three standard segments: fertility and early embryonic development, embryo-fetal development, and pre/postnatal development. All were conducted in rats; the embryo-fetal segment was repeated in rabbits.

In the rat fertility study, males received vardenafil at doses up to 20 mg/kg/day for 28 days before mating through the mating period. No adverse effects on sperm parameters, mating behavior, or fertility indices were observed 2. Female rats given vardenafil showed no effects on estrous cycling or implantation at the same dose range.

The embryo-fetal studies in rats (up to 18 mg/kg/day) and rabbits (up to 6 mg/kg/day) found no evidence of teratogenicity or embryolethality at any tested dose. Fetal body weights, skeletal ossification patterns, and soft-tissue morphology were comparable to controls. The no-observed-adverse-effect level (NOAEL) in both species exceeded the MRHD by a substantial margin.

In the peri/postnatal study, rat dams received vardenafil from late gestation through weaning. Pup survival, growth, and developmental landmarks (incisor eruption, eye opening, surface righting reflex) were unaffected. These results collectively support the absence of a reproductive hazard signal in standard preclinical models, but the gap between animal models and human gestational physiology remains a limiting factor in extrapolation.

PDE5 Inhibitor Pharmacology and Theoretical Reproductive Concerns

Vardenafil works by selectively inhibiting phosphodiesterase type 5 (PDE5), the enzyme responsible for degrading cyclic guanosine monophosphate (cGMP) in vascular smooth muscle. By blocking PDE5, vardenafil increases cGMP concentrations, promoting vasodilation and enhanced blood flow 4.

PDE5 expression is not limited to penile tissue. The enzyme is present in pulmonary vasculature, platelets, and uterine smooth muscle. This distribution raises theoretical questions about PDE5 inhibitor effects on uterine blood flow and myometrial tone during pregnancy.

Sildenafil, a closely related PDE5 inhibitor, has been studied more extensively in pregnant populations. The STRIDER consortium (Sildenafil Therapy In Dismal prognosis Early-onset fetal growth Restriction) tested sildenafil 25 mg three times daily in pregnancies complicated by severe early-onset fetal growth restriction. The Dutch arm of STRIDER (N=216) was halted early after an interim analysis found a higher incidence of neonatal pulmonary hypertension in the sildenafil group compared with placebo (17 vs. 3 cases) 5.

No equivalent trial exists for vardenafil. The STRIDER findings cannot be directly applied to vardenafil because of differences in PDE5 selectivity, half-life (vardenafil ~4-5 hours vs. sildenafil ~3-5 hours), and tissue distribution. The signal does, however, reinforce a class-level concern: PDE5 inhibition during pregnancy may affect fetal pulmonary vascular development through pathways that animal models did not fully capture.

A 2020 systematic review published in The Lancet Child & Adolescent Health analyzed all STRIDER trial arms and concluded that sildenafil for fetal growth restriction does not improve perinatal outcomes and may cause harm 6. The review did not include vardenafil data because none existed, but the authors recommended caution with any PDE5 inhibitor use during pregnancy until more is understood about fetal pulmonary effects.

Lactation: What Is Known (and What Is Not)

No published data describe vardenafil concentrations in human breast milk. The drug's prescribing information does not address lactation beyond noting the absence of an indication in women 2.

From a pharmacokinetic standpoint, vardenafil has properties that suggest potential for milk transfer. Its molecular weight is 488.6 Da (below the ~800 Da threshold often associated with limited milk passage), oral bioavailability is approximately 15%, and protein binding is about 95% 4. High protein binding generally limits the free fraction available for transfer into milk, but the low molecular weight works in the opposite direction. Without measured milk-to-plasma ratios, net infant exposure cannot be estimated.

LactMed, the NIH's drugs-and-lactation database, does not contain a dedicated vardenafil entry as of May 2026. LactMed does include sildenafil, noting that "because of the lack of data on the use of sildenafil during breastfeeding, an alternate drug may be preferred" 7. This conservative stance from NIH applies with equal or greater force to vardenafil, for which even less human lactation pharmacology is available.

The American Academy of Pediatrics (AAP) has not classified vardenafil among drugs reviewed for breastfeeding compatibility. In the absence of any human milk data, the default clinical position is to avoid the drug in nursing mothers unless a specific, well-justified clinical scenario (such as an IRB-approved research protocol investigating pulmonary hypertension) dictates otherwise.

Off-Label PDE5 Inhibitor Research in Women

Although vardenafil itself has limited study in female populations, the broader PDE5 inhibitor class has attracted investigational interest in several gynecologic and obstetric conditions. Understanding these efforts provides context for why a clinician might encounter questions about vardenafil in a female patient.

Female sexual arousal disorder (FSAD) was explored as a potential indication for sildenafil in multiple trials during the early 2000s. Pfizer ultimately abandoned the program after Phase III results showed inconsistent efficacy 8. Vardenafil was never formally tested for FSAD in a published clinical trial.

Preeclampsia prevention is another area of interest. A 2019 Cochrane review examined vasodilators for prevention of preeclampsia and found insufficient evidence to recommend PDE5 inhibitors for this purpose 9. The review identified only small pilot studies, none of which used vardenafil.

Pulmonary arterial hypertension (PAH) in pregnancy is a rare but life-threatening condition. Sildenafil and tadalafil carry FDA approval for PAH (marketed as Revatio and Adcirca, respectively). Vardenafil does not have a PAH indication. Case reports describe sildenafil use in pregnant patients with PAH, but outcomes data are limited to case series and registry analyses 10. Extrapolating from sildenafil PAH data to justify vardenafil use during pregnancy would be speculative and clinically inappropriate without direct evidence.

Clinical Decision Framework for Prescribers

When a clinician encounters a scenario involving vardenafil and a patient of reproductive potential, the following evidence-based considerations apply.

Is the patient pregnant? Vardenafil has no indication in pregnancy. Animal data show no teratogenicity, but the STRIDER signal with sildenafil raises class-level concern about fetal pulmonary vascular effects. Do not prescribe vardenafil to a pregnant patient outside of a formal research setting with ethics board oversight.

Is the patient breastfeeding? No human milk data exist. Molecular characteristics suggest possible transfer. Avoid use. If the clinical question involves PAH management in a lactating patient, sildenafil or tadalafil (which have more published lactation data, though still limited) are more defensible choices to discuss with a pulmonologist.

Is the patient a male with a pregnant partner? This is the most common real-world scenario. Vardenafil is metabolized and cleared by the patient taking it. Seminal fluid transfer of pharmacologically active drug concentrations has not been demonstrated for PDE5 inhibitors. The Endocrine Society's 2018 guidelines on testosterone therapy note that PDE5 inhibitors do not impair spermatogenesis, unlike exogenous testosterone 11. A male partner's use of vardenafil for ED does not pose a known risk to a pregnancy.

Is the patient trying to conceive? For male patients, vardenafil does not suppress the hypothalamic-pituitary-gonadal axis or reduce sperm counts. The Porst et al. 2003 trial in men with diabetes-related ED reported efficacy without fertility-related adverse events across 12 weeks of treatment 1. PDE5 inhibitors have been studied as adjuncts to improve sperm motility in vitro, though this application remains experimental 12.

How Vardenafil Compares to Other PDE5 Inhibitors on Reproductive Safety Data

The pregnancy and lactation evidence base differs across PDE5 inhibitors, primarily because sildenafil's earlier approval (1998) and PAH indication generated more female exposure data.

Sildenafil has the most published human pregnancy data of any PDE5 inhibitor, driven largely by the STRIDER trials and PAH case series. Tadalafil, approved for PAH as Adcirca, has limited pregnancy case reports but at least has a clinical context (PAH management) in which female exposure occurs. Vardenafil and avanafil have essentially zero published human pregnancy or lactation exposure data.

All four PDE5 inhibitors held Category B ratings under the legacy system. All showed clean animal reproductive toxicology profiles. The differentiating factor is the volume of post-marketing human data, and on that metric, vardenafil ranks near the bottom of its class.

This gap is unlikely to close. With no female indication on the horizon and generic competition reducing sponsor investment in new studies, vardenafil-specific pregnancy or lactation data will probably remain absent. Clinicians needing to use a PDE5 inhibitor in a female patient (e.g., for PAH) should default to sildenafil or tadalafil, where at least some human exposure data, however imperfect, inform the risk discussion.

Reporting Exposures and Pharmacovigilance

If an inadvertent vardenafil exposure during pregnancy does occur, clinicians should report it to the FDA's MedWatch program (1-800-FDA-1088). Bayer's prescribing information does not reference a pregnancy exposure registry for vardenafil, and no active registry exists as of May 2026.

The Organization of Teratology Information Specialists (OTIS), now part of MotherToBaby, can provide individualized risk counseling for patients exposed to vardenafil during pregnancy. Their service (1-866-626-6847) draws on all available preclinical and clinical data to help patients and providers make informed decisions after an unplanned exposure 13.

Clinicians should document the timing, dose, and duration of exposure in the medical record. First-trimester exposures during organogenesis (weeks 3 through 8 post-conception) carry the highest theoretical concern for any drug with unknown human teratogenic potential, though the Category B animal data for vardenafil provide some reassurance that structural malformations are unlikely at therapeutic doses.