How to Check Drug Interactions: A Complete Guide

• Drug-drug: Two or more medications affecting each other, such as warfarin and aspirin increasing bleeding risk.
• Drug-food: Food or drink altering a drug, such as grapefruit juice affecting some statins.
• Drug-supplement: Herbal or nutritional supplements interacting with medication, such as St. John's Wort reducing the effect of some antidepressants.
• Drug-condition: A medication that is risky given an existing health condition, such as certain drugs during pregnancy or kidney disease.

Five steps

• Make a complete list. Include every prescription, OTC medicine, vitamin, and supplement, with doses.
• Use a drug interaction checker. Enter each item to screen for known interactions.
• Review severity. Focus first on high-risk interactions, then moderate and minor ones.
• Read the recommendation. Some interactions require avoiding the combination; others just need spacing out doses or monitoring.
• Confirm with a professional. Bring your list and the results to your pharmacist or doctor before making any change.

• High risk — Avoid the combination when possible; serious effects can occur.
• Moderate risk — Use with caution; may need monitoring or dose changes.
• Minor risk — Usually manageable; be aware of timing or mild effects.

• Blood thinners (like warfarin) with NSAIDs such as ibuprofen or aspirin — increased bleeding risk.
• Opioids with benzodiazepines — increased risk of dangerous respiratory depression.
• SSRIs with tramadol or certain migraine drugs — risk of serotonin syndrome.
• Multiple medications that cause drowsiness — additive sedation.

• Use one pharmacy so your pharmacist sees your full medication list.
• Keep an up-to-date medication list on your phone.
• Tell every provider about supplements and OTC products, not just prescriptions.
• Ask before starting anything new, including herbal remedies.
• Read labels for warnings about alcohol, food, and other drugs.

• Medication Dosage Calculator — weight- and age-based dosing
• Kidney Function Calculator — dosing adjustments
• Insulin Dosage Calculator — diabetes management