Stop drinking coffee immediately if you take any of these 8 medications | November 10, 2025

Coffee is a favorite morning ritual for many and a source of energy. Together with some medications, it can neutralize the benefits of treatment or increase unwanted effects. We found out which medications should not be combined with coffee and why.

How coffee interferes with medications

Researchers identify several main mechanisms:

Changes in absorption.  Coffee increases the acidity of gastric juice. This affects the dissolution of tablets and the speed at which they pass through the digestive tract. As a result, some medications are absorbed less well.

Complex formation.  Caffeine can bind to the molecules of some drugs. Such complexes are absorbed worse in the intestines. This is especially important for iron and thyroxine preparations.

Enzyme competition.  In the liver, caffeine breaks down the enzyme CYP1A2. Antidepressants, neuroleptics, melatonin, and other drugs “compete” for the same enzyme. When the enzyme load is too high, drugs are eliminated from the body more slowly and the risk of side effects increases.

Additional stimulation.  Caffeine itself activates the nervous system. When taken with other stimulants, the effect is additive: anxiety, insomnia, and a rapid heart rate may occur.

Thyroid medications

In hypothyroidism, the thyroid gland produces too little hormone, which causes fatigue, weight gain, dry skin, and other symptoms. Levothyroxine is most often prescribed for treatment.

Coffee interferes with its absorption. Clinical observations show that if you drink coffee with a pill, the amount of the drug entering the bloodstream can be reduced by almost half. Because of this, the treatment becomes less effective.

Osteoporosis medications

In osteoporosis, bones become brittle. For prevention and treatment, drugs from the bisphosphonate group are used. These drugs should be taken only with water. If you take them with coffee or another drink, their absorption is reduced by more than half. As a result, the drug has almost no effect and the risk of fractures remains high.

Antidepressants

Coffee can reduce their effectiveness and increase side effects. If you drink coffee with amitriptyline or escitalopram, less of the active substance will enter the bloodstream. Therefore, the therapeutic effect is reduced.

Fluvoxamine is worth mentioning separately. It affects the liver enzymes that break down caffeine. As a result, the coffee acts longer and more strongly: insomnia, rapid heartbeat and anxiety may occur.

Antipsychotic drugs

They are used to treat schizophrenia, bipolar disorder, major depression, and other mental illnesses. Among the most well-known are clozapine, haloperidol, olanzapine, and aripiprazole.

Coffee reduces the absorption of these substances and affects their metabolism in the liver. As a result, less active substance enters the blood and the therapeutic effect weakens.

Clozapine is particularly susceptible to this interaction. It competes with caffeine for liver enzymes, slowing its breakdown. Studies have shown that plasma concentrations of clozapine increase by 97% after drinking 2-3 cups of coffee (about 400 milligrams of caffeine).

Blood pressure medications

Propranolol, metoprolol, and verapamil help reduce the workload on the heart and reduce the risk of stroke. If you drink coffee with these medications, their absorption is reduced. As a result, the effect is weaker: blood pressure may remain elevated despite treatment.

Anticoagulants

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