Many people around the world start their day with a cup of their comforting, energizing, daily cup of coffee.
But while your morning brew may feel harmless, it can interact with certain medications in ways that reduce its effectiveness — or increase the risk of side effects.
From 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 does not seem to affect people in the same way. Here’s what you need to know about how coffee can affect your medications.
1. Cold and flu medications
Caffeine is a stimulant, meaning it speeds up the central nervous system. Pseudoephedrine, a decongestant found in cold and flu medications, is also a stimulant that works in the same way.
When taken together, the effects may be increased, potentially causing jitters or restlessness, headaches, fast heart rate and insomnia.
2. Thyroid medication
Levothyroxine, the standard treatment for an underactive thyroid, is very sensitive to timing and your morning coffee can get in the way.
Research shows that drinking coffee too soon after taking levothyroxine can reduce its absorption by up to 50 percent. Why does this happen?
Caffeine actually speeds up intestinal motility (the movement of food and waste through the digestive tract), giving the thyroid medication less time to be absorbed
These effects reduce the bioavailability of the drug, meaning less of it reaches your bloodstream where it is needed.
If levothyroxine absorption is reduced, symptoms of hypothyroidism, including fatigue, weight gain, and constipation, may return, even if you take 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 antidepressants commonly used to treat depression, anxiety, and other psychiatric conditions. Laboratory studies suggest that caffeine from coffee may bind to these medications in the stomach, reducing absorption and possibly making them less effective.
4. Painkillers
Some over-the-counter pain relievers, such as those containing aspirin or acetaminophen, contain added caffeine. Coffee can speed up the rate at which these medications are absorbed by speeding up how quickly the stomach empties, making the stomach more acidic, which improves the absorption of some medications, such as aspirin.
While this can make painkillers work faster, it can also increase the risk of side effects such as stomach irritation or bleeding, especially when combined with other sources of caffeine.
Even though no serious cases have been reported so far, caution is still advised.
5. Heart medications
Caffeine can temporarily increase blood pressure and heart rate, which typically lasts three to four hours after consumption.
For people taking blood pressure medications or medications that control irregular heart rhythms (arrhythmias), this can counteract the intended effects of the medication.
This doesn’t mean that people with heart disease should avoid coffee altogether; they should see how this affects their symptoms and consider limiting intake or switching to decaffeinated coffee if necessary.
So, what to do?
If you are not sure whether your medicine and your coffee are harmful to you, consult your pharmacist or doctor. A quick conversation can save you weeks of side effects or reduced treatment effectiveness, as well as help you enjoy your daily coffee with peace of mind.
