Plan B and CBD — interaction profile and FAQ
Cannabidiol (CBD) is widely used as an over-the-counter wellness product, and many people taking Plan B (Levonorgestrel) — used for Plan B is indicated for emergency contraception after unprotected intercourse or known/suspected contraceptive failure, in women of reproductive age. — wonder whether the two are safe to combine. Unlike most herbal products, CBD has documented interactions with several drug-metabolising enzymes, which means it can change blood levels of co-administered medications. Below is a focused look at the Plan B-and-CBD question at the 1.5mg dosing strengths.
How CBD can affect Plan B blood levels
CBD inhibits several cytochrome P450 enzymes — most notably CYP3A4, CYP2C19 and CYP2D6 — which together metabolise a large fraction of prescription medications. Plan B, with active ingredient Levonorgestrel, may or may not be metabolised by these enzymes; if it is, concomitant CBD can raise Plan B blood levels and increase the risk of dose-related side effects. Conversely, in some pathways, induction or competition for transporters can lower exposure. The clinically relevant size of this effect depends on the CBD dose, formulation and individual hepatic metabolism.
Practical guidance for combined use
According to general clinical guidance, anyone planning to combine Plan B at the 1.5mg doses with regular CBD use should discuss this with the prescriber and ideally check the Plan B prescribing information and an interaction database (e.g. Lexicomp, the FDA Drug Interactions guidance) for the Levonorgestrel entry. Practical steps include starting at low CBD doses, separating CBD and Plan B doses by several hours where feasible and monitoring for side effects (sedation, dizziness, gastrointestinal symptoms or laboratory changes) during the first weeks. Pure isolate CBD has fewer co-formulants but the CYP-inhibition signal is similar.
Frequently asked questions
Is it safe to use CBD with Plan B? ▾
Whether CBD is safe to combine with Plan B depends on the metabolic pathway of Levonorgestrel, the CBD dose and the indication for which Plan B is taken at the 1.5mg dose. For many medications the interaction is mild and manageable; for narrow-therapeutic-index drugs (anticoagulants, anti-epileptics, immunosuppressants and some psychiatric medications) the combination warrants closer follow-up. Discuss with the prescriber and check an interaction database before starting CBD.
How much time should I leave between CBD and Plan B? ▾
For most medications, separating CBD and Plan B by several hours reduces, though does not eliminate, the metabolic interaction; for steady-state regimens with cumulative drug levels, simple time separation has limited effect. According to general pharmacological principles, the more meaningful step is establishing a stable CBD dose, monitoring symptoms and laboratory values, and adjusting Plan B dosing under the prescriber's guidance rather than relying on timing alone.
More on Plan B
- With alcoholPlan B and alcohol — is it safe to drink?
- With foodShould Plan B be taken with food?
- Side effectsPlan B side effects: common, rare and warning signs
- Dosage guidePlan B dosage guide: how much to take and when
- OnsetHow fast does Plan B start working?
- DurationHow long does Plan B last?
The information on this website is provided for reference and educational purposes only. It does not replace consultation with a qualified healthcare professional.