MDMA and Ritonavir (and cobicistat)
Can cause a dangerous, even fatal, MDMA overdose - never combine.
Why this happens
Ritonavir (and the similar booster cobicistat) strongly blocks CYP2D6, the liver enzyme that clears MDMA. A normal MDMA dose can then build to many times the expected blood level; a documented fatal case reached roughly ten times the expected concentration.
What this means in practice
Do not combine. If you take ritonavir or cobicistat - found in some HIV regimens and in Paxlovid - treat MDMA as off-limits and speak to an HIV pharmacist first.
Warning signs - get help
Call your local emergency number straight away if you notice any of these:
- A body temperature that stays high
- Chest pain or a racing, pounding heart
- Confusion, collapse or a seizure
Information, not medical advice. Threshold does not promote or encourage MDMA use. This exists so that people who make their own choices can make safer, better-informed ones. It is not a substitute for professional care.
Sources
- Fatal interaction between ritonavir and MDMA (Henry, Hill) - The Lancet (1998)
- Surviving life-threatening MDMA toxicity caused by ritonavir - Journal of Antimicrobial Chemotherapy (2012)