1. Antidepressants
Osei-Boamah recommends separating your coffee and antidepressant consumption by at least one to two hours to minimize the risk of interactions.
2. Cold and Allergy Medications
The stimulant effect of caffeine doesn’t pair well with many cold and allergy medicines. “Many cold medications, especially those with decongestants like pseudoephedrine, already increase heart rate or blood pressure,” says Kennedy Erickson, PharmD, a pharmacist with Centralia Pharmacy in Centralia, Washington, and a member of the American Pharmacists Association.
Adding caffeine can compound those effects, leading to heart palpitations or anxiety, Dr. Osei-Boamah adds.
Whether you’re taking OTC cold and allergy medications or prescription ones, it’s important to talk to your doctor about the potential side effects of combining them with coffee.
3. Thyroid Medicines
Erickson recommends taking levothyroxine on an empty stomach with water and waiting at least 30 to 60 minutes before drinking coffee. “It’s a simple timing fix that can make a big difference for thyroid control,” she says.
4. Diabetes Medications
“Caffeine can raise blood sugar levels in some individuals by triggering stress hormone release, which counteracts what many diabetes medications are trying to achieve,” says Erickson. “That said, the effect varies by individual, as some people are more sensitive to caffeine than others.”
The interaction between coffee and diabetes medication is complex. It depends on the effects of the caffeine and polyphenols (the main active ingredients in coffee) and your specific diabetes medication, adds Osei-Boamah.
5. Blood Pressure Medications
Caffeine can temporarily raise blood pressure, which may dampen the effectiveness of blood pressure medications. “This effect is most pronounced within the first one to three hours after ingestion,” says Osei-Boamah, noting that caffeine can raise systolic blood pressure (the pressure in your arteries when your heart contracts) by approximately 5 to 8 millimeters of mercury (mmHg) and diastolic blood pressure (the pressure in your arteries when your heart relaxes) by 4 to 6 mmHg, in sensitive individuals.
Still, if you’re taking blood pressure medication, your doctor may recommend avoiding caffeine altogether. “While it may not cancel out a blood pressure medication entirely, it can make control more difficult,” Erickson explains.
6. Osteoporosis Medications
Caffeine can significantly lower the absorption of oral bisphosphonates (such as alendronate, risedronate, and ibandronate), the first-line medications for osteoporosis (a bone-weakening disease), and, as a result, their bioavailability (the amount of the medicine that is available to the body), says Osei-Boamah.
“It’s recommended that oral bisphosphonates be taken with plain water only, at least 30 to 60 minutes before consuming coffee, other beverages, food, or supplements, to maximize absorption and clinical benefit,” adds Osei-Boamah.
One exception is the delayed-release formulation of risedronate, which is designed to be taken after breakfast with minimal impact on absorption and bioavailability, Osei-Boamah adds.
7. Melatonin
The way caffeine interacts with melatonin (the supplement form of a natural hormone that signals the body to prepare for sleep) is relatively straightforward. As a stimulant, caffeine counteracts melatonin’s sleep-promoting effects and delays its production, says Erickson.
8. Alzheimer’s Medications
9. Asthma Medications
“This is particularly true of theophylline, which is chemically similar to caffeine [both are stimulants],” says Erickson. “When taken together, they can lead to additive side effects like tremor, rapid heartbeat, or nausea. Even with inhalers like albuterol, caffeine may increase stimulation.”
10. Blood Thinners
The consistency of your coffee intake may impact whether you experience interactions. “If you take warfarin and drink a cup of coffee daily, that should not dramatically change how quickly blood clots,” Erickson says. “But adding a cup or two [more] a day could, so it’s important to track this.”
Coffee does not directly interact with newer blood thinners, such as apixaban or rivaroxaban, she adds.
When to See a Doctor
Talk to your doctor or pharmacist if you have questions about how coffee may interact with your medications, or if you experience side effects such as jitters, sleep disturbances, a fast heartbeat, blood sugar changes, or any other unusual symptoms. Your doctor can provide advice tailored to your specific medication.
“Sometimes, it’s not about eliminating coffee — it’s about spacing it properly,” says Erickson. You may be able to avoid interactions by adjusting the timing of your coffee and medications. However, some people may need to avoid coffee altogether.
It’s best to consult your healthcare provider for personalized recommendations tailored to the medicines you take, your sensitivity to caffeine, and any symptoms you experience.