Clarithromycin
Clarithromycin is a macrolide antibiotic that blocks the bacterial ribosome, stopping protein synthesis and the bacteria's ability to multiply. It is used for bacterial infections and, as part of combination treatment, for ulcers linked to Helicobacter pylori. It is also a strong inhibitor of the liver enzymes that clear many other medicines.
It can be taken with or without food, but grapefruit is avoided because it compounds the same enzyme blockade and pushes drug levels up. That blockade is why simvastatin and atorvastatin are not combined with it, and why the effect of warfarin can rise; omeprazole levels also shift, though the two are deliberately paired in ulcer treatment. Probiotics are kept a few hours apart, the course is finished in full, and ALT and creatinine are checked since the liver and kidneys both handle the drug.
Because clarithromycin can prolong the QT interval, palpitations, fainting or a markedly irregular heartbeat call for prompt medical attention. Muscle pain or weakness, dark urine, yellow skin or eyes, unusual bruising or bleeding, or severe persistent diarrhoea are reasons to see a doctor.
Reference information, not medical advice. Discuss any change with your doctor.