contraindication
12 interactions related to contraindication
sertraline + st. john's wort
Sertraline is an SSRI that blocks serotonin reuptake, and St. John's wort independently inhibits serotonin reuptake and contains constituents (hyperforin, hypericin) that elevate central serotonin. Combining them can trigger serotonin syndrome, a potentially life-threatening syndrome of altered mental status, autonomic instability, and neuromuscular hyperactivity. St. John's wort also induces CYP3A4 and CYP2C19, which can lower sertraline plasma levels and undermine treatment.
duloxetine + st. john's wort
Duloxetine is a serotonin-norepinephrine reuptake inhibitor (SNRI), and St. John's wort independently raises central serotonin through reuptake inhibition. Combined use can precipitate serotonin syndrome, and St. John's wort induction of CYP3A4 and P-glycoprotein may also alter duloxetine exposure.
metronidazole + alcohol
Metronidazole can produce a disulfiram-like reaction when combined with alcohol, causing flushing, nausea, vomiting, abdominal cramps, headache, and tachycardia. The FDA label warns against alcohol use during therapy and for at least 3 days afterward.
azathioprine + allopurinol
Allopurinol inhibits xanthine oxidase, the enzyme responsible for inactivating azathioprine's active metabolite 6-mercaptopurine. Combined use shunts more 6-MP into the active 6-thioguanine pathway, increasing azathioprine's effects 3-4 fold and producing potentially fatal myelosuppression, pancytopenia, and hepatotoxicity.
maoi + 5-htp
5-HTP is the direct precursor to serotonin and bypasses the rate-limiting step of serotonin synthesis. Combined with an MAOI, which blocks serotonin breakdown, intracellular and synaptic serotonin can rise to toxic levels, producing serotonin syndrome.
spironolactone + potassium
Spironolactone is a mineralocorticoid receptor antagonist that blocks aldosterone-driven potassium excretion in the collecting duct, causing the kidneys to retain potassium. Adding a potassium supplement, salt substitute, or potassium-rich diet on top of spironolactone can produce fatal hyperkalemia, especially in patients with chronic kidney disease, heart failure, diabetes, or who are also on an ACE inhibitor or ARB.
paroxetine + st. john's wort
Paroxetine is an SSRI with potent serotonin reuptake inhibition; St. John's wort independently inhibits serotonin reuptake and induces CYP3A4 and P-glycoprotein. The combination can precipitate serotonin syndrome and is among the most frequently reported SSRI plus St. John's wort interactions in published case series.
venlafaxine + st. john's wort
Venlafaxine is a serotonin-norepinephrine reuptake inhibitor (SNRI). St. John's wort independently inhibits serotonin (and to a lesser extent norepinephrine and dopamine) reuptake. Combining them can drive a sharp rise in synaptic serotonin and trigger serotonin syndrome, and St. John's wort can also alter venlafaxine pharmacokinetics through CYP3A4 induction.
fluoxetine + st. john's wort
Fluoxetine is an SSRI with a very long half-life (its active metabolite norfluoxetine persists for weeks), and St. John's wort independently raises serotonin via reuptake inhibition. Combined use can precipitate serotonin syndrome and, because of fluoxetine's slow elimination, the risk window extends well beyond the day of last dose.
probiotics + immunosuppressants
Live probiotic bacteria can translocate across the gut wall and cause bacteremia, endocarditis, or sepsis in patients whose immune systems are pharmacologically suppressed (e.g., calcineurin inhibitors, mTOR inhibitors, corticosteroids, mycophenolate). Multiple case reports document Lactobacillus and Bifidobacterium bloodstream infections in solid-organ and stem-cell transplant recipients.
escitalopram + st. john's wort
Escitalopram is a highly selective SSRI metabolized largely by CYP2C19 and CYP3A4. St. John's wort independently inhibits serotonin reuptake and strongly induces these same enzymes plus P-glycoprotein. Combined use risks serotonin syndrome and can also lower escitalopram plasma levels, blunting its antidepressant effect.
smoking + oral contraceptives
Smoking while using estrogen-containing oral contraceptives synergistically increases the risk of serious cardiovascular events including myocardial infarction, stroke, and venous thromboembolism. The risk is especially pronounced in women over 35 and increases with the number of cigarettes smoked.