Medications you should not take with caffeine

Before taking any medication, talk to your doctor.  PHOTO | COURTESY

What you need to know:

  • Interactions between caffeinated beverages and prescription drugs can lead to potentially dangerous effects, such as making the drugs less effective, making your conditions worse and increasing your risk of side effects. 

For many people, a morning cup of coffee starts their day. For others, it is a caffeinated soda after a meal or an energy drink for that boost of energy needed to complete tasks. However, did you know that all beverages that contain caffeine interact with some medications that you may be taking? 

In other words, they can alter how fast those medicines are absorbed into your bloodstream and drinking a caffeinated beverage at the same time as your medication may affect how well the medicine works for you. 

Experts say caffeine consumption affects the absorption, distribution, metabolism (breakdown) and elimination of many drugs. For example, diuretic drugs (water pills) decrease potassium while caffeine decreases potassium. So, taking them together can lead to low blood potassium levels.

Asthma medication

Asthma, a chronic disease that affects the lungs, also makes the airways inflamed and irritated. This causes difficulty breathing, coughing, wheezing as well as chest rigidity. 

Dr Wasswa Franklin, a general physician at Entebbe Grade B Hospital, says during a flare-up, people with asthma take medicines which help to relax the airways. However, these also often come with side effects such as restlessness, headaches, stomach pain and irritability. 

“Drinking beverages high in caffeine not only worsens the side effects but also affects how much of the medication is absorbed and used in the body,” Dr Wasswa warns.

Diabetes medicine

There are more than 500 million people living with diabetes and many of these take medication daily. Mixing coffee with sugar or milk can lead to a spike in blood sugar and impact how well your diabetes medication works. 

In a study by the American Diabetes Association, it was discovered that drinking anything with caffeine, such as coffee, could raise your insulin and blood sugar levels. In addition to that, studies show that caffeine may worsen symptoms for people with diabetes.

Hypertension medicine

Globally, more than 1.5 billion people have high blood pressure. This non-communicable disease, if not well controlled, increases one’s risk of heart disease and stroke. Dr Charity Asaba, a general practitioner at St Catherine Hospital in Kampala, says this is the reason why people with high blood pressure must take medication to keep it in check. 

“These medications work by slowing down your heart rate. Drinking coffee at the same time as taking blood pressure medications can cause less of the medicine to be absorbed by the body, thereby not getting the full benefit of the medicine,” Dr Asaba. 


The body makes melatonin, a natural hormone that helps you feel sleepy at night. People with sleep problems may be prescribed this over the counter supplement to ease their sleep. 

Caffeine on the other hand is a stimulant. If such a person takes a caffeinated beverage, it will make them feel more awake and make it hard to sleep even when you take the medication.  

Antidepressants & antipsychotic medicine

Antidepressants can help with depression, a mood disorder that affects how you feel and function. According to the Centre for Disease Control and Prevention (CDC), one in 10 teens and adults take antidepressant medications daily. They are the most prescribed drugs for adults in their 20s and 30s, and their use has increased dramatically over the last few decades. 

However, Dr Wasswa says, caffeine can affect how the body uses antidepressant medications since these will be metabolised differently if one takes caffeinated drinks while taking them. 

Fluvoxamine for instance is known to enhance insomnia and heart palpitations as side effects. These can be worsened by drinking coffee. 

Thyroid medicine

If you have hypothyroidism, it means that your thyroid is not producing enough thyroid hormone. This can cause weight gain, dry skin, joint pain, hair loss and irregular menstrual periods.

“In such a case, the doctor will prescribe thyroid medications to help balance your hormones. Drinking coffee while taking thyroid medication can reduce how much of your medicine is absorbed by the body, making the medicine less effective for you,” Dr Wasswa says.

Osteoporosis medication

Osteoporosis makes bones thin and fragile, which increases the risk of bone fracture. It is more common in women who have already gone through menopause.

Drugs such as risedronate or ibandronate treat osteoporosis but if taken at the same time as coffee, they will be less effective. In order to get the full effectiveness of this medicine, it is better to swallow the medicines with plain water.

Alzheimer's medicine

Alzheimer’s disease, a disorder of the brain that results in a loss of cognitive function, making it difficult to think, remember, or go about your daily tasks mostly affects people older than 65.

Dr Asaba says medicines given work by protecting the neurotransmitter acetylcholine. When taken with caffeine, these medicines can cause tightening of the blood-brain barrier and can decrease how much of the drug goes to your brain. 

She adds, however, that not all medications have bad interactions with coffee. It is, therefore, important to ask your doctor before you take the medication. 

Dairy products and medicine
Some medications not be taken with calcium-rich dairy products, including milk, yoghurt, cheese and ice cream. This is because the calcium can bind to the medication and affect how it works in your body potentially making it less effective.

“Antibiotics used to treat respiratory tract and urinary tract infections and osteoporosis medications, thyroid medication, and iron supplements are more commonly associated with potential dairy product interactions,” Dr Charity Asaba, a general practitioner at St Catherine Hospital in Kampala, says.

For example, she adds, tetracycline, minocycline, doxycycline, ciprofloxacin (Cipro), levofloxacin (Levaquin), and moxifloxacin (Avelox), ferrous sulfate and ferrous gluconate should not be taken with milk.