Caffeine and medication: What coffee triggers in the body

For millions of people, the first cup of coffee marks the true start of the day.

But for anyone taking long-term medication, that morning ritual can involve more than just comfort.

Reporting from Bild, supported by insights from pharmaceutical experts, highlights how caffeine can alter the effects of many medications — sometimes accelerating them, sometimes undermining them.

Faster relief

In certain drugs, caffeine works as an amplifier. Research in pharmacology shows that common painkillers such as paracetamol, ibuprofen and acetylsalicylic acid can be absorbed more rapidly when caffeine is present.

That is why some combination tablets deliberately include about 100 milligrams of the stimulant.

A strong espresso or mocha can intensify this boost.

Still, pharmacists caution against relying on caffeine to enhance medication long-term.

With repeated use, the body may adapt to the pairing, weakening the desired effect over time.

When coffee interferes

But caffeine’s influence is not always beneficial.

According to Bild, citing assessments from the State Chamber of Pharmacists of Baden-Württemberg, stimulants can counteract the effectiveness of medicines designed to calm the nervous system.

This applies to sedatives such as diazepam, certain H1 antihistamines and some antidepressants.

The reason is straightforward: caffeine’s energizing action directly conflicts with the intended therapeutic effect, potentially blunting the benefits for patients who depend on stable dosing.

Overlapping pathways

A particular concern arises for people taking theophylline, a treatment used in asthma and COPD.

Both caffeine and theophylline are processed by the liver through similar metabolic routes. If consumed close together, caffeine can slow the breakdown of theophylline.

This may raise drug levels in the bloodstream, increasing the risk of restlessness, palpitations or disturbed sleep.

Specialists recommend that patients using theophylline seek advice on how much caffeine is safe to consume and when.

Hormonal and metabolic effects

Caffeine can also influence blood sugar regulation.

Clinical studies indicate short-term spikes in glucose levels and reduced insulin sensitivity — factors that matter for people with diabetes or pre-diabetic conditions.

For those taking thyroid hormones, timing is key.

Coffee can reduce the intestinal absorption of L-thyroxine, making the treatment less effective.

Endocrinology guidelines advise waiting at least 30 to 60 minutes between taking the medication and drinking coffee.

What patients should know

Because interactions vary widely — depending on the drug, dose, metabolism and timing — healthcare providers are the best source of personalised advice.

Anyone who regularly takes medication should coordinate seemingly minor habits, including the day’s first cup of coffee, with their treatment plan.

Sources: Bild; State Chamber of Pharmacists of Baden-Württemberg; pharmacological literature and clinical studies.

This article is made and published by Camilla Jessen, who may have used AI in the preparation