Can I take Cannabis and Clarithromycin together?
Drug interaction guide
Originally published 25 Jan 2026
Meets Patient’s editorial guidelines
- DownloadDownload
- Share
- Language
- Discussion
Taking clarithromycin with cannabis can significantly increase the levels of THC and CBD in your bloodstream. This can make the effects of cannabis much stronger and last longer than usual. You may experience increased drowsiness, dizziness, confusion, or a racing heart. There is also a small risk of an irregular heartbeat (heart palpitations).
In this article:
Continue reading below
Why this happens
Your liver uses a specific enzyme (called CYP3A4) to break down cannabis. Clarithromycin 'switches off' this enzyme, which prevents your body from clearing the cannabis. This leads to a buildup of the drug in your system. Additionally, both substances can occasionally affect your heart rhythm.
What you should do
It is best to avoid using cannabis while taking a course of clarithromycin. If you do choose to use both, start with a much lower dose of cannabis than usual and be aware that the effects will last longer. Seek medical help if you feel your heart racing or feel extremely dizzy.
Continue reading below
Using other medicines
Taking multiple medicines? Our Medicines Interaction Checker helps you check whether your prescriptions, over-the-counter medicines, and supplements are safe to take together. Simply search for your medicines to see potential interactions and what to do about them.
Disclaimer
This information is for general educational purposes only and should not be relied upon as a substitute for professional medical advice. Always consult your GP, pharmacist, or another qualified healthcare professional before making decisions about your medications. Individual circumstances may vary, and only a healthcare professional who knows your medical history can provide personalised guidance.
Patient picks for Drug interactions

Treatment and medication
Can I take Idapamide and Ramipril together?
Taking indapamide and ramipril together can cause your blood pressure to drop too low, especially when you first start the combination. This can make you feel dizzy, lightheaded, or faint. It can also put extra strain on your kidneys.

Treatment and medication
Can I take Bactrim and Venlafaxine dexcel together?
Taking these two medicines together can increase the risk of a rare but serious condition called serotonin syndrome. It can also lead to an imbalance of salts in your blood (low sodium) and, in some cases, may affect your heart rhythm.
Continue reading below
Article history
The information on this page is written and peer reviewed by qualified clinicians.
25 Jan 2026 | Originally published

Ask, share, connect.
Browse discussions, ask questions, and share experiences across hundreds of health topics.

Feeling unwell?
Assess your symptoms online for free
Sign up to the Patient newsletter
Your weekly dose of clear, trustworthy health advice - written to help you feel informed, confident and in control.
By subscribing you accept our Privacy Policy. You can unsubscribe at any time. We never sell your data.