The negative impact of combining certain medications with coffee: here are 13 you should always avoid

It’s a key part of millions of Americans’ morning routines: wake up, take your meds and make a cup of coffee. 

Using daily medications to manage ongoing health issues and relying on coffee to awaken a tired mind are common practices. However, experts caution that combining them may result in harmful side effects and serious health issues.

Pharmacists have pointed out the risks of pairing medications with coffee, ranging from a dangerous spike in blood pressure to heightened chances of uncontrolled bleeding. The potential negative consequences are outlined by experts in an interview with the Daily Mail.

Antidepressants 

Antidepressants already come with a long list of side effects, and some drugs can make it harder to safely consume coffee.  

Dr. Jennifer Bourgeois, a pharmacist and health specialist at SingleCare, emphasized the risks, stating, “Caffeine may interact with these medications and lead to risky elevations in blood pressure.”

This is because older classes of antidepressants, such as tricyclics and monoamine oxidase inhibitors (MAOIs), prevent the body from properly metabolizing caffeine.

Normally, caffeine is filtered out through the kidneys as urine, but these drugs interrupt the process, leaving caffeine lingering in the body longer.

Over time this can cause a sustained high heart rate and high blood pressure.

Dr HaVy Ngo-Hamilton, clinical consultant at BuzzRx and pharmacist at the University of Minnesota Medical Center, added that drugs like fluvoxamine, phenelzine (Nardil), tranylcypromine (Parnate) were the worst offenders. 

The CDC estimated that one in 10 Americans over the age of 12 take antidepressants, adding up to around 37 million people. 

Experts said there are no known interactions between caffeine and newer so-called selective serotonin reuptake inhibitors (SSRIs) like Zoloft, Lexapro, and Prozac.  

OTC cold and allergy medications

It is estimated that nearly three in four US adults use over-the-counter cold and allergy meds to tackle symptoms. 

Many of these contain the stimulant pseudoephedrine, which narrows blood vessels in the nasal passages to reduce swelling and congestion. 

However, by doing this, pseudoephedrine stimulates cells in the brain responsible for the ‘fight or flight’ response that keeps us safe when we are under threat.

Dr Ngo-Hamilton warned that drinking coffee alongside these meds can exacerbate symptoms and make you feel jittery and anxious.

She pointed to over-the-counter drugs such as Sudafed and Mucinex as popular products with pseudoephedrine, and recommended taking these medications two hours before or four hours after a cup of coffee. 

Diabetes medications

One in 10 Americans take insulin to manage their diabetes. And while insulin does not directly interact with caffeine, it can still clash with your morning coffee. 

‘It’s more like, when you drink coffee, it increases your blood sugar, especially if there’s cream and sugar in it too,’ Dr Ngo-Hamilton said. 

‘Your blood sugar will spike, and that is making your medication less effective.’ 

In fact, drinking anything with caffeine can increase insulin and blood sugar levels, according to research from the American Diabetes Association. 

In addition to insulin, Dr Ngo-Hamilton said people should also be mindful of the blood sugar drug metformin, which is taken by over 20 million Americans, according to the latest available data from 2021.

Dr Ngo-Hamilton recommended keeping track of your blood sugar to determine if you should drink coffee with your medications. 

Antibiotics

Antibiotics are prescribed for a wide variety of infections, with the CDC estimating that more than230 million such prescriptions were written in 2022 alone. 

However, these drugs can inhibit the metabolism of caffeine, leading to increased caffeine levels in the blood. 

Dr Bourgeois specifically pointed to ciprofloxacin, also known as Cipro, which is typically used for bacterial infections such as UTIs and bladder infections, infectious diarrhea, and sinus infections. 

As with cold and allergy meds, ‘this antibiotic can inhibit the metabolism of caffeine, leading to increased caffeine levels in the blood,’ she warned. 

And just like with OTC meds, taking this drug with coffee could lead to a racing heart and feeling jittery. 

Blood thinners

A survey by the National Blood Clot Alliance suggested that eight million Americans take blood thinners, which are used to prevent blood clots. 

Warfarin is both the oldest and most common, accounting for about a quarter of US blood thinner prescriptions, according to the Cleveland Clinic. 

Dr Ngo-Hamilton said caffeine can inhibit the breakdown of blood thinners, leading to more of the drug lingering in the body. 

This is particularly dangerous because having too much of the drug could result in excessive bleeding, even from minor injuries like a paper cut. 

For warfarin specifically, Dr Ngo-Hamilton recommends waiting ‘at least six to eight hours’ after taking the medication to have some coffee since there is ‘a very significant drug interaction between warfarin and caffeine.’

Newer blood thinners like Eliuis should not cause the these interactions, she noted. 

Blood pressure medications 

The American Association of Colleges of Pharmacy estimated that 117 million prescriptions for beta blockers have been doled out to 26 million Americans. 

These are meant to lower blood pressure and block the effects of the hormone epinephrine, or adrenaline. This helps improve blood flow and lower heart rate. 

‘Beta blockers work to reduce your heart rate so that your heart doesn’t have to work as hard,’ Dr Ngo-Hamilton said. 

‘But then when you drink coffee, or any caffeinated beverages, it increases your heart rate and ultimately increases your blood pressure. This is not a direct drug interaction, but it’s more like counteracting the beta blocker.’

She suggested taking these medications two hours before or four hours after a cup of coffee or other caffeinated drink. 

Thyroid medications 

Levothyroxine, which is designed to treat an underactive thyroid – hypothyroidism – is one of America’s most prescribed drugs, totaling 23 million prescriptions per year. 

However, Dr Ngo-Hamilton cautioned that taking these drugs with any type of food or water – coffee included – can reduce the amount of medication absorbed by the body. 

One review from 2020 found that caffeine reduced this absorption rate by as much as 50 percent.  

Dr William Franklin, founder and medical director of Victory Medical in Texas, told the Daily Mail that people with levothyroxine prescriptions should take the drug ‘on an empty stomach with water and wait 30 to 60 minutes before having caffeine’. 

Alzheimer’s medications 

Experts estimated that one in 10 US adults over the age of 65 have been diagnosed with Alzheimer’s disease, the most common form of dementia. 

Medications to treat symptoms, called cholinesterase inhibitors, prevent the breakdown of acetylcholine – a chemical that helps with memory formation and thinking. 

However, taking these drugs with coffee tightens the blood-brain barrier, making it more difficult for the medication to reach the brain. 

‘Ultimately, it reduces the effectiveness,’ Dr Ngo-Hamilton said. 

She pointed to Donepezil and Rivastigmine as the most likely culprits to cause this effect. 

She also noted that someone on these drugs should take them two hours before or four hours after coffee.  

Osteoporosis medications 

Osteoporosis is where bones become weak or brittle over time, causing even minor stressors like coughing to fracture them. 

The CDC estimated that 10million Americans aged over 50 live with the condition and take medications like risendronate and ibandronate to slow bone breakdown.

However, as with thyroid medications, taking these drugs with coffee can stop them being properly absorbed by the body, making them less effective.

Dr Ngo-Hamilton recommended waiting about two hours after taking the medication to drink coffee or eat food. 

Asthma medications

Many of the 25 million Americans living with asthma rely on bronchodilators, a class of prescription medications that relax and widen the airways. 

However, mixing bronchodilators such as aminophylline and theophylline with coffee could exacerbate the side effects of these drugs – like irritability and restlessness.

‘If you’re new on the medication, wait and see how you’re doing on the medication first before you start drinking coffee because it can worsen the side effects,’ Dr Ngo-Hamilton said. 

If you do still want to drink coffee, she suggested taking these medications four hours before or after.

ADHD medications

Close to one in 10 Americans under the age of 17 have been diagnosed with ADHD, according to CDC data, and about 41million prescriptions have been doled out.

These drugs help regulate neurotransmitters like dopamine and norepinephrine to improve focus, attention and impulse control. 

However, taking drugs such as Adderall and Ritalin with coffee could make them less effective and lead to increased hyperactivity.  

‘Both ADHD medications and caffeine are stimulants. When combined, they can amplify each other’s effects, leading to overstimulation,’ Dr Bourgeois said.

Antipsychotics

Roughly four million Americans take some form of antipsychotic medication, according to the Cleveland Clinic.

Some of the most common examples include clozapine, risperidone, and olanzapine, which are typically prescribed for severe mention health conditions such as schizophrenia and bipolar disorder.

These work by regulating neurotransmitters like dopamine and serotonin to mitigate symptoms that include hallucinations.

However, Dr Ngo-Hamilton warned that coffee can reduce how much of the medication is absorbed by the body. And if a person is suffering from mania, the drugs would then be unable to pull them out of it. 

She recommended staying away from coffee altogether if a patient is having a manic episode.