Dangerous Combination: common drug interactions you should know

Mixing medications, supplements, or alcohol can turn a helpful treatment into a dangerous problem. Some combos raise bleeding risk, others crash your blood pressure, and a few can damage your liver or kidneys. You don’t need to memorize every interaction—know the big ones and how to check when you add a new drug.

Common risky mixes

NSAIDs (like Celebrex/celecoxib or meloxicam) + ACE inhibitors (like Vasotec/enalapril) or certain diuretics: this trio can harm kidney function. If you’re on an ACE inhibitor for blood pressure and take NSAIDs for pain, your kidneys can lose protection and stop working as well—watch for less urine, swelling, or fatigue.

SSRIs (fluoxetine/Sarafem) + NSAIDs or blood thinners: SSRIs increase bleeding risk, especially if you add an NSAID or warfarin. That means more nosebleeds, bruises, or heavier periods. Ask your doctor before combining these.

SSRIs (fluoxetine) + other serotonergic drugs (triptans, certain migraine drugs, tramadol): stacking drugs that boost serotonin raises the risk of serotonin syndrome—confusion, fast heart rate, shaking, or high temperature. It looks scary and needs immediate attention.

PDE5 inhibitors (erectile dysfunction meds) + nitrates: this is one of the clearest “never combine” rules. Together they can drop blood pressure to dangerous levels. If you use nitrates for chest pain, don’t take PDE5 drugs without a doctor’s okay.

Opioids (hydrocodone) + benzodiazepines or alcohol: this mix can slow breathing and cause overdose. If you’re using pain meds, avoid sedatives unless your prescriber closely monitors you.

Antibiotics or antifungals (like Lamisil/terbinafine) + other liver-stressing drugs or heavy alcohol use: terbinafine can strain the liver. Combining several liver-impacting medicines raises the chance of liver damage.

Glucose-lowering drugs (Rybelsus/semaglutide) + insulin or sulfonylureas: combining these increases hypoglycemia risk. Watch blood sugar closely and adjust doses with your clinician.

How to avoid dangerous combos

Always tell your doctor and pharmacist everything you take: prescriptions, OTC meds, vitamins, and herbs. Use one pharmacy so they can spot interactions. Before starting a new drug, ask: "Does this interact with what I already take?" Check reliable interaction tools and print out the result to discuss with your clinician.

If you get a new symptom after adding a medicine—dizziness, heavy bleeding, confusion, fainting, dark urine—stop and call your provider. Don’t guess. A quick call can prevent a serious event. Simple habits—full med lists, single pharmacy, and asking the right questions—cuts the risk of dangerous combinations dramatically.

Need help checking a specific mix? Bring your full med list to your next appointment or use a trusted interaction checker online and then confirm with a pharmacist.