Codeine (Tylenol #3) and Ketamine Therapy | Tovani Health
Tylenol #3 (Codeine) (also: Tylenol with Codeine) — Opioid analgesic (mu-receptor agonist prodrug)
Verdict at Tovani Health
Compatible; CYP2D6 ultra-rapid metabolizers can convert codeine to morphine too efficiently.
Codeine and ketamine are compatible. Standard opioid-sedation precautions apply. One specific to flag: codeine is a prodrug converted to morphine by CYP2D6, and ultra-rapid metabolizers (about 1-2% of patients) generate much higher morphine levels than expected. Combined with ketamine, this means the respiratory depression in those patients can be more pronounced than the prescribed dose suggests.
If you take Tylenol #3 regularly and are considering at-home ketamine therapy, the combination is safe with monitoring or dose adjustment. This page covers the brief pharmacologic context and what we do at intake.
How Tylenol #3 interacts with ketamine
Codeine itself has weak opioid activity; the analgesic effect comes from CYP2D6 conversion to morphine. Genetic variation in CYP2D6 produces a 10-100x range in active morphine produced from the same codeine dose.
What we do at intake
Tell us if you have ever had pharmacogenomic testing or know your CYP2D6 status. Disclose dose and frequency.
Bottom line
Codeine and ketamine are compatible. Standard opioid-sedation precautions apply. One specific to flag: codeine is a prodrug converted to morphine by CYP2D6, and ultra-rapid metabolizers (about 1-2% of patients) generate much higher morphine levels than expected. Combined with ketamine, this means the respiratory depression in those patients can be more pronounced than the prescribed dose suggests.
Frequently Asked Questions
Should I avoid codeine if I do not know my CYP2D6 status?
Not necessarily. Most patients metabolize codeine normally. We just want you to disclose use so we can plan around it.
Ready to find out if at-home ketamine fits your situation?
We’ll note that you’re on Tylenol #3 (Codeine) 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.
Sources
The verdict and clinical guidance on this page are based on the following peer-reviewed literature and FDA prescribing information.
- Ketamine as an adjuvant to opioids for cancer pain. Bell RF, Eccleston C, Kalso EA.. Cochrane Database of Systematic Reviews. 2017. PMID: 28657160
Cochrane systematic review evaluating ketamine added to opioid therapy for cancer pain.
- Attenuation of Antidepressant Effects of Ketamine by Opioid Receptor Antagonism. Williams NR, Heifets BD, Blasey C, et al.. American Journal of Psychiatry. 2018. PMID: 30153752
Landmark study showing pretreatment with naltrexone (opioid receptor antagonist) blocks the antidepressant effect of ketamine.
Clinically reviewed
Reviewed by Benjamin Soffer, DO on May 16, 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.