Drug interactions
Caffeine + Phenobarbital
Severity: Minor
Caffeine and Phenobarbital: minor interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Caffeine may oppose the sedative effect of phenobarbital. In addition, phenobarbital induces CYP1A2 and may increase caffeine clearance, and caffeine may lower the seizure threshold at high intake.
What this interaction means in plain words
Caffeine and Phenobarbital have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Why it happens
Pharmacodynamic opposition via adenosine blockade, plus CYP1A2 induction by phenobarbital that speeds caffeine metabolism.
What to do
Counsel patients to keep caffeine intake moderate and consistent. Monitor seizure control in epilepsy patients who consume large amounts of caffeine.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Caffeine
- Caffeine + Ephedrine Major
- Caffeine + Fezolinetant Major
- Caffeine + Methylenedioxymethamphetamine Major
- Caffeine + Selegiline transdermal Major
- Adenosine + Caffeine Moderate
- Benzphetamine + Caffeine Moderate
Frequently asked questions
Can I take Caffeine with Phenobarbital?
MediHelp rates the interaction as minor. Caffeine and Phenobarbital have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Caffeine may oppose the sedative effect of phenobarbital. In addition, phenobarbital induces CYP1A2 and may increase caffeine clearance, and caffeine may lower the seizure threshold at high intake.
How serious is the interaction between Caffeine and Phenobarbital?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Counsel patients to keep caffeine intake moderate and consistent. Monitor seizure control in epilepsy patients who consume large amounts of caffeine.
What other medicines interact with Caffeine?
MediHelp also lists interactions of Caffeine with, for example, Ephedrine, Fezolinetant, Methylenedioxymethamphetamine. The full list is on the Caffeine page.
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