Thyroid hormone replacement
Levothyroxine and cannabis (marijuana, THC)
As cannabis becomes legal or decriminalised in more jurisdictions, the practical question of combining it with prescription medication comes up regularly. Levothyroxine (Levothyroxine) and cannabis share several pharmacological pathways, and the combination at 25mcg, 50mcg, 75mcg, 100mcg, 150mcg is not automatically benign even where both are legal.
How cannabis affects Levothyroxine
THC and other cannabinoids are metabolised partly by hepatic CYP enzymes, including CYP3A4 — the same pathway used by many Thyroid hormone replacement medications. Frequent cannabis use can shift the metabolism of Levothyroxine mildly. THC also has cardiovascular effects (increased heart rate, blood pressure changes) and central nervous system effects that can stack with Levothyroxine's side-effect profile.
Practical guidance
Occasional moderate cannabis use is unlikely to cause clinically meaningful problems for most adults on Levothyroxine at 25mcg, 50mcg, 75mcg, 100mcg, 150mcg. Heavy daily use, edibles with high THC content, or cannabis combined with alcohol substantially raise the risk of dizziness, hypotension, impaired judgement and amplified side effects from Levothyroxine. According to the prescribing information, the full list of recreational substances should be disclosed to the prescriber.
Frequently asked questions
Can I use cannabis while taking Levothyroxine? ▾
For most adults at 25mcg, 50mcg, 75mcg, 100mcg, 150mcg, occasional moderate cannabis is tolerated, but heavy daily use is not advised because of metabolic and additive cardiovascular effects with Levothyroxine. The safe practice is to mention it to the prescriber.
Does CBD interact with Levothyroxine? ▾
CBD inhibits several CYP enzymes including CYP3A4, which can raise plasma levels of medications that go through that pathway. For Levothyroxine specifically, this depends on whether Levothyroxine uses CYP3A4. Daily high-dose CBD products warrant a pharmacist check.
Products containing Levothyroxine
More on Levothyroxine
- With alcoholLevothyroxine and alcohol — is it safe to drink?
- With foodShould Levothyroxine be taken with food?
- Side effectsLevothyroxine side effects: common, rare and warning signs
- Dosage guideLevothyroxine dosage guide: how much to take and when
- OnsetHow fast does Levothyroxine start working?
- DurationHow long does Levothyroxine last?
The information on this website is provided for reference and educational purposes only. It does not replace consultation with a qualified healthcare professional.