Topical Terbinafine Safety in Pregnancy
Topical terbinafine can be safely used during pregnancy, as high-quality evidence demonstrates no increased risk of major malformations, spontaneous abortion, or adverse pregnancy outcomes.
Evidence Supporting Safety
The most robust evidence comes from a 2020 nationwide Danish registry study examining 1,650,649 pregnancies, which found:
- No increased risk of major malformations with topical terbinafine exposure (prevalence odds ratio 1.08,95% CI 0.81-1.44; absolute risk difference 0.26%) 1
- No increased risk of spontaneous abortion (hazard ratio 1.04,95% CI 0.88-1.21; absolute risk difference 0.17%) 1
- No increased risk of preterm birth, low birth weight, or stillbirth 2
A 2022 systematic review corroborated these findings, concluding that both systemic and topical terbinafine exposure during pregnancy showed no association with congenital malformations or adverse pregnancy outcomes 2.
Clinical Recommendations
For fungal skin infections in pregnancy:
- Topical terbinafine may be utilized after first-line topical agents (clotrimazole, miconazole, nystatin) have been considered 3
- The 2017 European Academy of Dermatology review classifies topical terbinafine as safe for use in pregnancy, though recommending it as a second-line option after the above agents 3
Mechanism Supporting Safety Profile
Topical formulations have limited systemic absorption, which substantially reduces fetal exposure compared to oral medications 3, 4. This pharmacokinetic property provides a biological rationale for the safety observed in epidemiological studies.
Important Caveats
- While topical terbinafine appears safe, first-line topical antifungals (clotrimazole, miconazole, nystatin) remain preferred due to more extensive safety data in pregnancy 3
- The evidence supporting topical terbinafine safety is stronger than for many other antifungal agents, but decades of clinical experience favor the traditional first-line agents 4, 5
- Avoid oral terbinafine unless absolutely necessary, though even oral formulations showed no increased risk in the Danish study (prevalence odds ratio 1.01 for malformations) 1
Practical Application
When treating dermatomycoses in pregnant patients:
- Start with clotrimazole, miconazole, or nystatin as first-line topical therapy 3
- Consider topical terbinafine if first-line agents fail or are not tolerated 3
- Reassure patients that topical terbinafine exposure does not require pregnancy termination or additional fetal monitoring based on current evidence 2, 1
The current FDA pregnancy category recommendations for terbinafine should be reconsidered given the accumulating evidence of safety 2.