Singulair 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. Singulair (Montelukast) and cannabis share several pharmacological pathways, and the combination at 4mg, 5mg, 10mg is not automatically benign even where both are legal.
How cannabis affects Singulair
THC and other cannabinoids are metabolised partly by hepatic CYP enzymes, including CYP3A4 — the same pathway used by many Respiratory Medications medications. Frequent cannabis use can shift the metabolism of Montelukast mildly. THC also has cardiovascular effects (increased heart rate, blood pressure changes) and central nervous system effects that can stack with Singulair's side-effect profile.
Practical guidance
Occasional moderate cannabis use is unlikely to cause clinically meaningful problems for most adults on Singulair at 4mg, 5mg, 10mg. 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 Montelukast. 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 Singulair? ▾
For most adults at 4mg, 5mg, 10mg, occasional moderate cannabis is tolerated, but heavy daily use is not advised because of metabolic and additive cardiovascular effects with Montelukast. The safe practice is to mention it to the prescriber.
Does CBD interact with Singulair? ▾
CBD inhibits several CYP enzymes including CYP3A4, which can raise plasma levels of medications that go through that pathway. For Singulair specifically, this depends on whether Montelukast uses CYP3A4. Daily high-dose CBD products warrant a pharmacist check.
More on Singulair
- With alcoholSingulair and alcohol — is it safe to drink?
- With foodShould Singulair be taken with food?
- Side effectsSingulair side effects: common, rare and warning signs
- Dosage guideSingulair dosage guide: how much to take and when
- OnsetHow fast does Singulair start working?
- DurationHow long does Singulair last?
The information on this website is provided for reference and educational purposes only. It does not replace consultation with a qualified healthcare professional.