Medications You Shouldn’t Mix With Your Coffee

Most of us don’t think twice before having a cup of coffee in the morning. But if you’re taking certain medications, that caffeine boost may do more harm than good. Some drugs don’t mix well with coffee or caffeine – they can work less effectively or cause unwanted side effects. Here’s a look at which ones to watch out for – and when it might be worth switching to tea.

Caffeine can actually make common pain relievers like ibuprofen, paracetamol, or acetaminophen work better. One review found that people who took an over-the-counter painkiller along with 100 milligrams of caffeine – roughly what’s in a strong cup of coffee – got roughly 10% more pain relief. Researchers aren’t exactly sure why this happens, but they think caffeine may help your body absorb medication and keep it in your system longer. Ibuprofen isn’t sold with caffeine added, but you can try taking a 200-milligram dose alongside your morning coffee.

Many over-the-counter cold and allergy medications contain pseudoephedrine, a decongestant that also acts as a stimulant. Taking it with coffee can make you feel jittery, restless, or unable to sleep, so it’s best not to have them at the same time. This combo can also raise blood sugar levels, so be especially careful if you have diabetes. If your allergy medication doesn’t contain pseudoephedrine, like Benadryl, it can make you drowsy, which means it won’t interact with caffeine in the same way. To keep side effects in check, try adjusting the timing of your medication, stick to a regular sleep schedule, and limit how much alcohol you drink. 

Some blood pressure medications work by slowing down your heart rate so your heart doesn’t have to work as hard to pump blood. Caffeine can have the opposite effect, raising your heart rate and making these medications less effective. Other drugs, like Verelan, lower blood pressure by relaxing your blood vessels, and caffeine can interfere with that, too. Over the long term, higher blood pressure raises your chances of health problems like heart disease, heart attacks, and strokes. If you need a natural pick-me-up, try snacks with healthy carbs, fats, and protein instead.  

Medications like warfarin help prevent clots by keeping your blood thin enough to flow easily through your arteries and veins. Since caffeine can also slow down your blood’s ability to clot, drinking coffee while taking these medications could make you bruise or bleed more easily. You may not have to give up coffee completely, but it’s best to stick to small amounts and check with your doctor to find out what’s safe for you. 

If you take levothyroxine for an underactive thyroid, coffee can interfere with how your body absorbs the medication. That means it may not work as well against symptoms like fatigue, weight gain, constipation, and sensitivity to cold. The good news is that you don’t have to give up coffee altogether – just wait 30 minutes to an hour after taking your medication before having your first cup.

Caffeine affects different types of antidepressants in different ways. Some research suggests that it may help SSRIs like fluoxetine or fluvoxamine stay in your system longer, which could make them work better. On the other hand, coffee can make some people feel anxious or interfere with sleep, which may worsen some depression symptoms. Taking high doses of caffeine combined with MAOIs, like phenelzine and tranylcypromine, may also raise your chances of having high blood pressure. Because the effects can vary, it’s a good idea to check with your doctor about how much caffeine is safe if you’re taking antidepressants.

Caffeine on its own can make anxiety, hostility, sleep problems, and other symptoms of psychotic disorders worse. It can also affect how your body processes antipsychotic medications, which might make them less effective. This happens because caffeine and many antipsychotics are broken down by the same enzyme, meaning your body may struggle to handle both at the same time. Make sure to talk to your doctor about how to adjust your caffeine intake so your medication works as well as it should.

If you have diabetes, caffeine can affect how your body uses insulin, which may cause an unwanted drop or spike in blood sugar. Some research suggests it takes about 200 milligrams of caffeine – roughly two strong cups of coffee – to trigger this effect, and people with type 2 diabetes may be more sensitive. Everyone reacts differently, but if you have a hard time controlling your blood sugar, try cutting back on caffeine to see if it helps.  

Asthma drugs like theophylline work by relaxing the muscles around your airways, making it easier for you to breathe. Caffeine is chemically similar to theophylline and can cause a milder version of the same effect, so some research suggests it might offer a small benefit for people with asthma. But because both caffeine and asthma medication can cause side effects like restlessness and crankiness, having both in your system at the same time may make those symptoms worse.

Antibiotics from the quinolone family slow down the enzymes that normally help you break down the caffeine in a cup of coffee, meaning it can stay in your system for longer. As a result, you might feel jittery or have trouble sleeping. These effects can vary, depending on the antibiotic. Research shows that enoxacin has the strongest reaction to caffeine, while ofloxacin may have a milder one. If you’re taking quinolone antibiotics and need a morning boost, try going for a walk or getting some fresh air – both have been shown to increase energy naturally.

Methotrexate helps treat autoimmune conditions, like arthritis and psoriasis, by lowering inflammation. Research on how caffeine affects the drug is mixed. Some studies suggest it might make methotrexate less effective, while others show little to no impact. Since the evidence isn’t clear, it’s best to keep your caffeine intake moderate. That includes coffee, tea, energy drinks, and chocolate.

Drinking coffee and other types of caffeinated beverages can tighten the blood-brain barrier – a protective layer around your brain’s blood vessels that controls what gets in and out. When it’s tighter, some drugs have a harder time reaching your brain. These include Alzheimer’s medications like donepezil, galantamine, and rivastigmine. Simple alternatives like breathing exercises, staying hydrated, or taking a short nap if you get tired can help boost energy without affecting your medication.