One pill, many questions: could emergency contraception briefly alter blood vessel health?

NCT ID NCT07759635

Recruiting now Knowledge-focused Sponsor: McMaster University Source: ClinicalTrials.gov ↗

First seen Aug 12, 2026 · Last updated Aug 13, 2026 · Updated 1 time

Summary

This trial investigates whether a single dose of the emergency contraceptive Plan B (levonorgestrel) affects markers of blood clotting and blood vessel function in young, healthy, premenopausal women. Participants will have their blood and artery function measured before and at several time points after taking either Plan B or a placebo. The goal is to understand if this common pill has any short-term cardiovascular effects.

What this could mean

Our plain-language read of the trial. This is informational only — not medical advice or a prediction.

Active substance: A single 1.5 mg dose of levonorgestrel (Plan B), an emergency contraceptive pill
What this could lead to: If it works, this could reveal whether a single emergency contraceptive dose has any short-term effects on blood clotting or artery health, informing safer use.
What could go wrong: This is a small, early study in healthy young women, so results may not apply to other groups. It only looks at short-term markers, not actual clot events, and the effects may be minimal or absent.

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Conditions

The condition(s) this trial relates to.

Venous Thrombosis

As listed by the trial registrant

The condition terms exactly as the trial's registrant entered them.

FEMALE PREMENOPAUSAL

Contacts and locations

Locations

Vascular Dynamics Lab
RECRUITING

Hamilton, Ontario, L8S 4L8, Canada

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