No Drug Interaction Between Sertraline and Plan B
Sertraline does not reduce the effectiveness of Plan B (levonorgestrel) emergency contraception. There is no documented pharmacological interaction between selective serotonin reuptake inhibitors (SSRIs) like sertraline and levonorgestrel-based emergency contraceptives 1.
Why Plan B Remains Fully Effective
Plan B works through a hormonal mechanism (primarily by preventing or delaying ovulation) that is completely independent of serotonin pathways 1.
The FDA label for Plan B makes no mention of SSRI interactions or any contraindication with antidepressants, and formal drug-drug interaction studies would have identified any clinically significant interference 1.
Sertraline's mechanism of action involves selective inhibition of serotonin reuptake in the central nervous system and has no effect on progestin metabolism or the hypothalamic-pituitary-ovarian axis at therapeutic doses 2.
Clinical Guidance for Emergency Contraception Use
Plan B should be taken as soon as possible within 72 hours of unprotected intercourse, regardless of concurrent sertraline use 3, 1.
Efficacy is time-dependent: Plan B reduces the expected pregnancy rate from 8% to approximately 1% when taken promptly, with effectiveness decreasing after 72 hours 1.
The standard dosing is 1.5 mg levonorgestrel as a single dose (or two 0.75 mg tablets taken together), and this regimen remains unchanged for patients on sertraline 3, 4.
Important Considerations
If ulipristal acetate (Ella) is chosen instead of levonorgestrel, it may be more effective 3-5 days after intercourse and in women with higher body weight, but again, sertraline does not interfere with its mechanism 3, 4.
The copper IUD remains the most effective emergency contraceptive option (essentially 100% effective) and can be inserted up to 5 days after unprotected intercourse, with no interaction concerns related to sertraline 4, 5.
Common side effects of Plan B (menstrual changes, nausea, abdominal pain, fatigue) are unrelated to sertraline co-administration 1.
Practical Counseling Points
Advise patients that:
- Sertraline will not interfere with Plan B's ability to prevent pregnancy 1.
- They should take Plan B as directed without adjusting their sertraline dose 3, 1.
- If vomiting occurs within 2 hours of taking Plan B, they should contact their provider to discuss repeating the dose—this precaution applies to all users, not specifically those on sertraline 1.
- A pregnancy test is warranted if their period is delayed more than one week beyond the expected date 1.