For most people, the day is incomplete without the first cup of coffee. While it is not just comforting and energising – coffee is also one of the most consumed beverages in the world. And so, while your morning brew may be harmless, it can interact with a few medicines in ways that reduce their effectiveness – or increase the risk of side effects.

According to experts, caffeine has a major impact on medication like tablets for the common cold to even antidepressants, as it makes your body go far beyond a quick energy boost. And even though tea also contains caffeine, it does not have the same concentration as coffee, and the effect is much less. Here are a few medications you need to be wary of.

The stimulant properties of caffeine, like pseudoephedrine, can amplify effects like increased heart rate, jitters, and insomnia, speeding up the central nervous system. When you drink coffee along with the medicines, the effects get amplified, and since many cold medications already contain added caffeine, it spikes the risks further.

According to studies, if you combine caffeine with pseudoephedrine, it also raises blood sugar and body temperature, which is particularly important for people with diabetes. Doctors say these effects are also concerning when you combine them with ADHD medicines like amphetamines or with asthma drugs such as theophylline – both of which share a similar chemical structure to caffeine.

Coffee interferes with the absorption of thyroid medication, especially levothyroxine – commonly used to treat hypothyroidism. It is generally recommended to wait at least 30-60 minutes after taking thyroid medication before consuming coffee to mini potential interference.

According to doctors, levothyroxine is extremely sensitive to timing – and your morning coffee does get in the way. Studies say coffee too soon after you take levothyroxine reduces its absorption by up to 50 per cent. Caffeine also speeds up gut motility, giving the drug less time to be absorbed – and may also bind to it in the stomach, making it harder for the body to take in.

A few commonly available painkillers like paracetamol, Combiflam, or even aspirin include added caffeine. So, if you drink coffee along with the tablet, it can speed up how quickly these drugs get absorbed by accelerating how fast the stomach empties and making the stomach more acidic. While it can 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. Though no serious cases have been reported, caution is still advised.

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, also known as arrhythmias, this may counteract the intended effects of the medication. However, it does not mean people with heart conditions must avoid coffee altogether – but they should monitor how it affects their symptoms and consider limiting intake or switching to decaf if needed.