antibiotic
11 interactions related to antibiotic
doxycycline + iron
Iron forms an insoluble chelate complex with doxycycline in the gastrointestinal tract, dramatically reducing absorption of the antibiotic. Studies show ferrous sulfate co-administration can lower doxycycline serum levels by 80% or more, potentially leading to treatment failure.
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.
tetracycline + zinc
Zinc forms a chelate with tetracycline in the gastrointestinal tract, reducing absorption of the antibiotic by approximately 30 percent. The interaction also reduces zinc absorption.
tetracycline + calcium
Calcium binds tightly to tetracycline in the gut, forming an insoluble chelate that cannot be absorbed. Dairy products and calcium supplements can reduce tetracycline absorption by 50 to 90 percent, often dropping serum levels below the threshold needed to treat infection.
doxycycline + calcium
Calcium chelates doxycycline in the gut, forming an insoluble complex that cannot be absorbed. Co-administration with calcium supplements or dairy products can reduce doxycycline absorption by 50 to 80 percent.
caffeine + ciprofloxacin
Ciprofloxacin is a potent CYP1A2 inhibitor. Co-administration increases caffeine's area-under-the-curve by 50-100% and prolongs its half-life, producing exaggerated central nervous system and cardiovascular stimulation.
aged cheese + linezolid
Linezolid is a reversible monoamine oxidase inhibitor, and aged cheeses (cheddar, parmesan, blue cheese, brie, gruyere) accumulate large amounts of tyramine through protein breakdown during aging. With MAO inhibited, ingested tyramine triggers massive norepinephrine release and can produce a hypertensive crisis with severe headache, palpitations, and blood pressure spikes of 30 to 50 mmHg within 30 to 120 minutes.
levofloxacin + calcium
Calcium chelates levofloxacin in the gastrointestinal tract, reducing peak serum concentrations by 20 to 30 percent. While the area under the curve is less affected than with older fluoroquinolones, the drop in peak concentration can matter for organisms with MICs close to the breakpoint.
doxycycline + magnesium
Magnesium ions chelate doxycycline in the gastrointestinal tract, forming an insoluble complex that markedly reduces antibiotic absorption. Magnesium-containing antacids and supplements can lower doxycycline bioavailability by up to 90 percent.
dairy + fluoroquinolones
Calcium and magnesium in dairy products chelate with fluoroquinolone antibiotics (ciprofloxacin, levofloxacin, moxifloxacin) in the gut, forming insoluble complexes that the body cannot absorb. Co-ingestion can reduce fluoroquinolone bioavailability by 30-50%, potentially causing treatment failure.
coffee + ciprofloxacin
Ciprofloxacin is a potent inhibitor of CYP1A2, the enzyme that metabolizes caffeine. Co-administration can reduce caffeine clearance by 30% to 50% and prolong its half-life, leading to higher plasma caffeine levels, jitteriness, insomnia, palpitations, tremor, and (rarely) seizures.