Cimetidine (Tagamet) and Ketamine Therapy | Tovani Health
Tagamet (Cimetidine) (also: Tagamet HB) — H2 receptor antagonist (OTC heartburn)
Verdict at Tovani Health
Fully compatible with KAP; cimetidine's famous CYP inhibitions don't affect ketamine.
Cimetidine and ketamine have no clinically significant interaction. Cimetidine is famous for inhibiting CYP1A2, CYP2C9, and CYP2D6 — leading to documented interactions with warfarin, theophylline, propranolol, TCAs, and phenytoin. But ketamine is metabolized primarily by CYP3A4 and CYP2B6, which cimetidine doesn't meaningfully affect. The big-named interactions are with other drugs, not KAP.
If you take Tagamet regularly and are considering at-home ketamine therapy, the combination is generally safe at therapeutic doses. This page covers the brief pharmacologic context and what we do at intake.
How Tagamet interacts with ketamine
Cimetidine blocks histamine H2 receptors on gastric parietal cells. Its CYP1A2/2C9/2D6 inhibition is real and matters for many drugs, but ketamine's CYP3A4/2B6 metabolism is essentially untouched.
What we do at intake
Continue as needed. Tell us about other medications — cimetidine's interactions with warfarin/theophylline/etc. matter for those, even though they don't matter for KAP.
Bottom line
Cimetidine and ketamine have no clinically significant interaction. Cimetidine is famous for inhibiting CYP1A2, CYP2C9, and CYP2D6 — leading to documented interactions with warfarin, theophylline, propranolol, TCAs, and phenytoin. But ketamine is metabolized primarily by CYP3A4 and CYP2B6, which cimetidine doesn't meaningfully affect. The big-named interactions are with other drugs, not KAP.
Ready to find out if at-home ketamine fits your situation?
We’ll note that you’re on Tagamet (Cimetidine) at intake. The eligibility check takes 5 minutes and gives you an honest answer about whether at-home ketamine fits your specific situation.
FL and NJ residents only. Benjamin Soffer, DO — Tovani Health.
Clinically reviewed
Reviewed by Benjamin Soffer, DO on May 22, 2026. Dr. Soffer is a board-certified physician (American Board of Internal Medicine) licensed in Florida and New Jersey, prescribing at-home ketamine therapy through Tovani Health.
This page is general information about how this medication interacts with at-home ketamine therapy at Tovani Health. It is not a substitute for medical advice from your prescribing physician about your specific situation. Always discuss medication changes with the doctor who prescribed them.