Clarithromycin, sold under the brand name Biaxin among others, is an antibiotic used to treat various bacterial infections.

[11] Clarithromycin is primarily used to treat a number of bacterial infections including pneumonia, Helicobacter pylori, and as an alternative to penicillin in strep throat.

[13] The American Academy of Sleep Medicine's 2021 clinical practice guidelines conditionally suggested its use, especially for those who don't respond to other therapies.

[20] Common adverse effects of clarithromycin in the central nervous system include dizziness, headaches.

[12] Clarithromycin inhibits a liver enzyme, CYP3A4, involved in the metabolism of many other commonly prescribed drugs.

Taking clarithromycin with other medications that are metabolized by CYP3A4 may lead to unexpected increases or decreases in drug levels.

Clarithromycin has been observed to have a dangerous interaction with colchicine as the result of inhibition of CYP3A4 metabolism and P-glycoprotein transport.

Combining these two drugs may lead to fatal colchicine toxicity, particularly in people with chronic kidney disease.

[23] Concurrent therapy with calcium channel blocker may increase risk of low blood pressure, kidney failure, and death, compared to pairing calcium channel blockers with azithromycin, a drug similar to clarithromycin but without CYP3A4 inhibition.

It binds to 23S rRNA, a component of the 50S subunit of the bacterial ribosome, thus inhibiting the translation of peptides.

[citation needed] In addition to its antibiotic activity, clarithromycin has been found to act as a negative allosteric modulator of the GABAA receptor.

Due to the high concentration in phagocytes, clarithromycin is actively transported to the site of infection.

[8] The product emerged through efforts to develop a version of the antibiotic erythromycin that did not experience acid instability in the digestive tract, causing side effects, such as nausea and stomachache.

[6] Clarithromycin is available under several brand names in many different countries, including Biaxin, Crixan, Claritron, Clarihexal, Clacid, Claritt, Clacee, Clarac, Clariwin, Claripen, Clarem, Claridar, Cloff, Fromilid, Infex, Kalixocin, Karicin, Klaricid, Klaridex, Klacid, Klaram, Klabax, Klerimed, MegaKlar, Monoclar, Resclar, Rithmo, Truclar, Vikrol and Zeclar.

[28] There was no apparent improvement on an objective measure of vigilance, but subjective sleepiness was reduced with the drug compared to placebo.