Allopurinol and Ketamine interaction
Allopurinol and Ketamine: both prescribing labels flag this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Ketamine (Ketalar) label · effective 2026-03-27
Theophylline or Aminophylline : Do not co-administer with KETALAR as concomitant use may lower the seizure threshold ( 7.1 ).
Consider using an alternative to KETALAR in patients receiving theophylline or aminophylline.
Drug Interactions Theophylline or Aminophylline : Concomitant administration of KETALAR and theophylline or aminophylline may lower the seizure threshold [see Drug Interactions ( 7.1 )] .
Theophylline or Aminophylline Concomitant administration of KETALAR and theophylline or aminophylline may lower the seizure threshold.
From the Allopurinol label · effective 2026-05-21
Inform patients also that the central nervous system depressant effects of allopurinol tablets may be additive to those of alcohol and other CNS depressants.
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.