How your daily coffee habit is affecting the way your medicine works

Many people across the globe, begin their day with a cup of their comforting, energizing, daily cup coffee.

But while your morning brew might feel harmless, it can interact with certain medicines in ways that reduce their effectiveness – or increase the risk of side effects.

From common cold tablets to antidepressants, caffeine’s impact on the body goes far beyond a quick burst of alertness.

Tea also contains caffeine but not in the same concentrations as coffee, and doesn’t seem to affect people in the same way. So, here’s what you need to know about how coffee can interfere with your medications.

1. Cold and flu medicines

Caffeine is a stimulant, which means it speeds up the central nervous system. Pseudoephedrine, a decongestant found in cold and flu remedies, is also a stimulant which works in the same way.

When taken together, the effects can be amplified, potentially leading to jitters or restlessness, headaches, a fast heart rate and insomnia.

2. Thyroid medication

Levothyroxine, the standard treatment for an underactive thyroid, is highly sensitive to timing and your morning coffee can get in the way.

Studies show that drinking coffee too soon after taking levothyroxine can reduce its absorption by up to 50 per cent. Why does this happen?

Caffeine basically speeds up gut motility (the movement of food and waste through the digestive tract), giving the thyroid medicine less time to be absorbed

These effects reduce the drug’s bioavailability, meaning less of it reaches your bloodstream where it’s needed.

If absorption of levothyroxine is impaired, symptoms of hypothyroidism which include fatigue, weight gain and constipation can return, even if you’re taking your medicine correctly.

3. Antidepressants and antipsychotics

The interaction between caffeine and mental health medications can be more complex.

Selective serotonin reuptake inhibitors (SSRIs), such as sertraline and citalopram, are a type of antidepressant medication widely used to treat depression, anxiety and other psychiatric conditions. Lab studies suggest caffeine from coffee can bind to these drugs in the stomach, reducing absorption and potentially making them less effective.

4. Painkillers

Some over-the-counter painkillers, such as those containing aspirin or paracetamol, include added caffeine. Coffee can speed up how quickly these drugs are absorbed by accelerating how fast the stomach empties, making the stomach more acidic, which improves absorption for some medications, such as aspirin.

While this may help painkillers work faster, it could also raise the risk of side effects like stomach irritation or bleeding, especially when combined with other sources of caffeine.

Even though no serious cases have been reported till yet, caution is still advised.

5. Heart medications

Caffeine can temporarily raise blood pressure and heart rate, typically lasting three to four hours after consumption.

For people taking blood pressure medication or drugs that control irregular heart rhythms (arrhythmias), this may counteract the intended effects of the medication.

This doesn’t mean people with heart conditions must avoid coffee altogether, they should see how it affects their symptoms, and consider limiting intake or switching to decaf if needed.

So, what to do?

If you’re ever unsure whether your medicine and your coffee would harm you, ask your pharmacist or doctor. A short conversation might save you weeks of side effects or reduced treatment effectiveness as well as help you enjoy your daily coffee with peace of mind.