How many hours after I have take terbinafine, can I drink coffee or soda?

Per terbinafine's package insert, caffeine (coffee, soda, chocolate) should be avoided because this medication may cause caffeine to stay in your body longer than usual. It decreases how fast the body gets rid of caffeine. Thus, taking caffeine along with it can increase the risk of caffeine side effects including jitteriness, headache, increased heartbeat, and other effects.

Terbinafine has a long half-life of 36 hours. From a clinical standpoint, it is assumed that a drug is effectively eliminated after 5 half-lives. Therefore, it would take 180 hours (7.5 days) for it to be eliminated and avoid any interaction with caffeine. It would, therefore, be best to avoid caffeine completely.

If drinking coffee before work is essential for you to be productive at work, you may talk with your doctor so he could assess your current health status and determine if a small amount of coffee intake will have a minimal risk to you.