liminfoDrug Interaction Checker
Free web tool: Drug Interaction Checker
Simplified interaction database. Always consult a pharmacist or prescriber for complete drug interaction checks.
About Drug Interaction Checker
The Drug Interaction Checker allows you to select multiple medications from a list of 30 commonly prescribed drugs and immediately see all known interactions between them, sorted by clinical severity. Interactions are classified as major (avoid or closely monitor — potentially life-threatening), moderate (use with caution — clinically significant effect), or minor (low clinical significance — monitoring may be warranted). Each result includes a brief clinical description explaining the mechanism or risk.
The database covers 35 clinically significant interaction pairs involving high-risk drug combinations that healthcare students, patients managing multiple medications, and caregivers should be aware of. Key interaction categories include anticoagulant-NSAID combinations (Warfarin + Aspirin/Ibuprofen/Naproxen — major bleeding risk), CYP enzyme interactions (Fluconazole inhibiting CYP2C9 elevating Warfarin; Omeprazole reducing Clopidogrel activation via CYP2C19), serotonin syndrome risk (SSRIs + Tramadol), benzodiazepine CNS depression stacking (Alprazolam + Diazepam), statin-related rhabdomyolysis risk (Simvastatin + Fluconazole or Cyclosporine), and lithium toxicity from impaired renal clearance.
This tool is intended for educational and informational purposes to help users understand potential drug interaction risks. The 30 included drugs are among the most commonly prescribed medications globally: anticoagulants (Warfarin, Rivaroxaban, Clopidogrel), NSAIDs (Aspirin, Ibuprofen, Naproxen, Acetaminophen), diabetes medications (Metformin), antihypertensives (Lisinopril, Amlodipine, Losartan, Hydrochlorothiazide), statins (Atorvastatin, Simvastatin), PPIs (Omeprazole), antidepressants (Sertraline, Fluoxetine), benzodiazepines (Alprazolam, Diazepam), and others. Always consult a pharmacist or physician for complete drug interaction screening.
Key Features
- Checks interactions between 30 commonly prescribed medications
- Database of 35 clinically significant interaction pairs
- Three severity levels: major (red), moderate (yellow), minor (blue)
- Each interaction includes a clinical description explaining the mechanism or risk
- Results sorted by severity — major interactions shown first
- Search bar to quickly find a specific drug in the list
- Toggle selection of multiple drugs simultaneously
- Educational disclaimer reminding users to consult a pharmacist
Frequently Asked Questions
What drugs are included in this interaction checker?
The tool includes 30 medications: Warfarin, Aspirin, Ibuprofen, Metformin, Lisinopril, Amlodipine, Atorvastatin, Simvastatin, Omeprazole, Metoprolol, Losartan, Hydrochlorothiazide, Amoxicillin, Ciprofloxacin, Fluconazole, Sertraline, Fluoxetine, Alprazolam, Diazepam, Prednisone, Digoxin, Clopidogrel, Rivaroxaban, Levothyroxine, Gabapentin, Tramadol, Acetaminophen, Naproxen, Cyclosporine, and Lithium.
What does "major" severity mean in drug interactions?
"Major" interactions are combinations where the risk of serious harm is well-documented and generally the combination should be avoided unless specifically indicated by a physician. Examples include Warfarin + Aspirin (greatly increased bleeding risk), Simvastatin + Fluconazole (contraindicated due to extreme rhabdomyolysis risk), and Alprazolam + Diazepam (combined CNS and respiratory depression from duplicate benzodiazepines).
Why does Warfarin interact with so many other drugs?
Warfarin is metabolized primarily by the CYP2C9 enzyme in the liver. Many drugs either inhibit CYP2C9 (slowing warfarin breakdown and raising its blood levels) or induce it (speeding breakdown and lowering levels). NSAIDs such as Ibuprofen and Naproxen also increase bleeding risk independently by inhibiting platelet function. Warfarin's narrow therapeutic index means even small changes in its level can result in dangerous under-anticoagulation or over-anticoagulation.
What is serotonin syndrome and which drug combinations can cause it?
Serotonin syndrome is a potentially life-threatening condition caused by excess serotonergic activity in the nervous system. Symptoms include agitation, rapid heart rate, high blood pressure, dilated pupils, muscle twitching, and in severe cases, hyperthermia and seizures. It can be triggered by combining SSRIs (Sertraline, Fluoxetine) with serotonergic drugs like Tramadol, which inhibits serotonin reuptake and increases serotonin levels.
Why is Omeprazole + Clopidogrel a major interaction?
Clopidogrel is a prodrug that must be converted to its active form by the CYP2C19 enzyme. Omeprazole is a potent CYP2C19 inhibitor, significantly reducing this conversion. This means patients taking both drugs may have substantially reduced antiplatelet protection, potentially increasing the risk of cardiovascular events such as stent thrombosis. Alternative PPIs like Pantoprazole have less CYP2C19 inhibition.
Is this drug interaction checker a replacement for consulting a pharmacist?
No. This tool is for educational and informational purposes only. It covers a simplified subset of known interactions and does not account for patient-specific factors such as renal function, hepatic function, dosage, other concurrent medications, or individual genetic variation in drug-metabolizing enzymes. Always consult a licensed pharmacist or prescribing physician for a complete drug interaction review before starting, stopping, or combining any medications.
Why is Lithium sensitive to interactions with NSAIDs and diuretics?
Lithium is eliminated entirely by the kidneys and has a very narrow therapeutic window. NSAIDs (Ibuprofen) reduce renal prostaglandin synthesis, decreasing renal blood flow and lithium clearance, which can raise lithium levels by 25–60%. ACE inhibitors (Lisinopril) and thiazide diuretics (Hydrochlorothiazide) similarly reduce renal lithium excretion. Even modest increases in lithium concentration can cause toxicity: tremor, nausea, confusion, and in severe cases, cardiac arrhythmias.
Is this drug interaction tool free to use?
Yes, completely free. No account or download is needed. The interaction database is built into the page and all processing runs locally in your browser. No health or medication data is stored or transmitted to any server.