Morning-After Pill and HPV Vaccine: No Interaction

There is no pharmacological or immunological interaction between emergency contraception (levonorgestrel or ulipristal acetate) and the human papillomavirus (HPV) vaccine. They can be administered at any interval without affecting each other’s efficacy or safety.

Mechanisms (Independent Pathways)

• Emergency Contraception: Levonorgestrel (progestin) delays ovulation; ulipristal acetate (SPRM) delays ovulation and may prevent implantation. Acts on hypothalamic-pituitary-ovarian axis.
• HPV Vaccine: Virus-like particles (VLPs) induce neutralizing antibodies against HPV capsid protein L1. Activates adaptive immunity (B cells, T follicular helper cells).

Clinical Guidance

• No need to delay HPV vaccination after EC, or vice versa.
• Both are safe and effective when given per schedule.
• HPV vaccine is recommended through age 26 (shared decision-making 27–45); EC is for post-coital use only, not routine contraception.

Concurrent administration is supported by CDC, ACOG, and WHO.