05/01/2026
Important Drug Interactions to Avoid ⚠️🚨
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1. Omeprazole + Clopidogrel
· Why avoid? Omeprazole inhibits the liver enzyme (CYP2C19) needed to activate clopidogrel, reducing its antiplatelet effect and increasing the risk of blood clots.
· Safer alternative: Pantoprazole (less effect on CYP2C19).
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2. Azithromycin + Antihistamines (e.g., cetirizine, loratadine)
· Why avoid? Both can prolong the QT interval, increasing the risk of serious heart arrhythmias (e.g., torsades de pointes).
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3. Ondansetron + Tramadol
· Why avoid? Ondansetron reduces the analgesic effect of tramadol by interfering with serotonin pathways.
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4. Antacids + Iron supplements
· Why avoid? Antacids reduce stomach acidity, impairing the absorption of iron (which requires an acidic environment).
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5. Metronidazole + Warfarin
· Why avoid? Metronidazole potentiates warfarin’s anticoagulant effect, significantly increasing the risk of severe or fatal bleeding.
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6. Calcium Channel Blockers (Verapamil/Diltiazem) + Beta-Blockers
· Why avoid? Combined use can cause severe bradycardia (slow heart rate), heart block, or hypotension.
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7. Sildenafil (Vi**ra) + Nitrates (e.g., nitroglycerin)
· Why avoid? Both cause vasodilation, which can lead to severe, potentially fatal hypotension.
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8. Furosemide + Aminoglycosides (Gentamicin/Amikacin)
· Why avoid? Increases the risk of ototoxicity (hearing loss or damage).
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9. Omega-3 supplements + Anticoagulants (e.g., warfarin, apixaban)
· Why avoid? Omega-3 has mild anticoagulant effects; combined use increases bleeding risk.
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10. Ciprofloxacin + Warfarin
· Why avoid? Ciprofloxacin potentiates warfarin’s effect, increasing bleeding risk. Monitor PT/INR closely and watch for bleeding signs.
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11. Metronidazole + Mebendazole
· Why avoid? Risk of severe skin reactions like Stevens-Johnson Syndrome (SJS).
· Safer alternative: Albendazole (trade name: Alzental).
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12. Septrin (Co-trimoxazole) + Uricol (Hexamine)
· Why avoid? Uricol acidifies urine, promoting sulfonamide (in Septrin) crystallization in the kidneys, leading to crystalluria, stones, or renal damage.
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13. Methylprednisolone + Clarithromycin
· Why avoid? Clarithromycin inhibits steroid metabolism, increasing methylprednisolone levels and the risk of side effects (e.g., immunosuppression, hyperglycemia).
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14. Buscopan (hyoscine) injection + Voltaren (diclofenac) injection
· Why avoid? Risk of precipitation when mixed in the same syringe or injection site, leading to local tissue damage or reduced efficacy.
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Other Notable Interactions:
· Aspirin + Ibuprofen – Both inhibit COX-2; ibuprofen can interfere with aspirin’s antiplatelet effect.
· Aspirin + Ticlopidine – Increased risk of gastric ulcers and impaired ulcer healing.
· ACE Inhibitors + Potassium supplements/potassium-sparing drugs – Risk of hyperkalemia.
· Digoxin + Verapamil/Diltiazem – Increased digoxin levels due to reduced renal clearance.
· Loop diuretics + NSAIDs – NSAIDs reduce diuretic efficacy by inhibiting renal prostaglandins.
· Tramadol + SSRIs/TCAs – Increased risk of serotonin syndrome and seizures.
· Tramadol + Quinidine – Quinidine inhibits tramadol metabolism, increasing its concentration and toxicity risk.