Question. Are there any psychotropics that have a negative interaction with caffeine? Is caffeine bad for people with certain disorders?
Answer. There are certainly psychotropics that can interact with caffeine in clinically important ways, though not always in bad ways.
First, though, it’s important to distinguish two types of drug-drug interactions. In one type of interaction called pharmacokinetic, one drug affects the metabolism of another. That is, one drug alters the way another drug is broken down or eliminated by the body. In the second type of interaction, called pharmacodynamic, one drug affects the way another drug acts on the brain. Caffeine may have both types of interactions with psychotropics. For example, caffeine can increase the excretion of the mood stabilizer, lithium, leading to reduced lithium levels in the blood. In theory, this could reduce the effectiveness of lithium in some patients.
On the other hand, caffeine may have a beneficial pharmacodynamic interaction when patients are taking sedative-hypnotics, such as Valium; i.e., caffeine seems to counteract the negative effects of the sedative on the brain, and thus improves cognitive performance.
Since caffeine can raise blood pressure and heart rate, it might not be wise to use it in patients whose psychotropic medications are already having these effects; for example, the antidepressant venlafaxine (Effexor) can raise blood pressure when used in high doses. However, many long-time coffee drinkers have probably developed a certain degree of tolerance to the effects of caffeine; i.e., they no longer react as strongly to it as they did years ago. In clinical practice, it’s rare that one or two cups of coffee per day (roughly, 100-200 mg of caffeine) will adversely affect most patients and/or their psychotropic medications; however, some patients with panic disorder are extremely sensitive even to tiny amounts of caffeine, and these patients should not use caffeinated products at all.
On the other hand, some patients taking highly-sedating psychotropics (such as the antipsychotic, clozapine) may actually benefit from 100-200 mg of caffeine per day, since it counteracts some of the drug’s sedation. In short – each case must be evaluated individually in order to decide whether caffeine will have beneficial or adverse effects on the patient.