Clarithromycin is an antibiotic. In the U.S., its brand name is Biaxin. In other countries it is known as Klacid and Mavid. Antibiotics fight infections caused by bacteria. Clarithromycin is also used to fight opportunistic infections (OIs) in people with HIV.


Clarithromycin is used for mild or moderate bacterial infections. It works against several different bacteria, especially chlamydia, hemophilus, and streptococcus. These bacteria can infect the skin, nose, throat, lungs, and ears.

Many germs live in our bodies or are common in our surroundings. A healthy immune system can fight them off or keep them under control. However, HIV infection can weaken the immune system. Infections that take advantage of weakened immune defenses are called opportunistic infections (OIs). People with advanced HIV disease can get OIs. Some people with very low CD4 cell counts (below 50 cells/mm3) take clarithromycin to prevent infections.

One OI in people with HIV is mycobacterium avium complex (MAC). People who have a CD4 cell count of less than 50 cells/mm3 may develop MAC.

Clarithromycin is often used with other antibiotics to treat MAC. It can also be used to prevent MAC infection. If your CD4 cell count is below 50 cells/mm3, talk to your healthcare provider about using clarithromycin.

Some people are allergic to clarithromycin and similar antibiotics. Be sure to tell your healthcare provider if you are allergic to clarithromycin or other antibiotics.


Whenever you take medication, be sure to take all of the prescribed doses. Many people stop if they feel better, but this is not a good idea. If the drug doesn’t kill all of the germs, they might change (mutate) so that they can survive even when you are taking medications. When this happens, the drug will stop working. This is called developing resistance to the drug.

For example, if you are taking clarithromycin to fight MAC and you miss too many doses, the MAC in your body could develop resistance to clarithromycin. Then you would have to take a different drug or combination of drugs to fight MAC.


Clarithromycin is available in tablets of 250 or 500 milligrams (mg.) It is also available in granules to prepare a liquid form. The dose and the length of time you will take it depend on the type of infection you have.

The dose used to prevent MAC infection is 500 mg every 12 hours. The treatment continues as long as your CD4 cell count is low enough for you to develop MAC. If your CD4 cell count goes above 100 cells/mm3 for 3-6 months, your healthcare provider may recommend stopping clarithromycin.

Be sure to talk with your healthcare provider
before you stop taking any of your prescribed medications. 

Regular clarithromycin tablets can be taken with or without food. Biaxin XL, an extended-release version, should be taken with food.


The side effects of clarithromycin mostly affect the digestive system. They include diarrhea, nausea, heartburn, and pain in the abdomen. Some people get headaches or rash. Very few people who take clarithromycin get these side effects. However, most antiretroviral medications (ARVs) used to treat HIV also cause problems in the digestive system. Clarithromycin could make those problems worse.

Clarithromycin can be hard on the liver. Your healthcare provider will probably watch your lab results carefully for any sign of liver damage. Let your healthcare provider know if your urine gets dark or your bowel movements get light-colored.

Antibiotics kill some helpful bacteria that normally live in the digestive system. You can eat yogurt or take supplements of acidophilus to replace them.


Clarithromycin is broken down by the liver. It can interact with other drugs that also use the liver. Scientists have not yet studied all the possible interactions. Clarithromycin probably interacts with all of the non-nucleoside reverse transcriptase inhibitors (NNRTIs), some blood thinners, heart medications, seizure medications, and other antibiotics. Be sure your healthcare provider knows about all the medications and supplements you are taking.

The class of drugs known as protease inhibitors (PIs) can increase blood levels of clarithromycin. These drugs include:


Clarithromycin is used to treat MAC, an opportunistic infection in people with HIV. It can prevent new infections or treat active infections. If your CD4 cell count is below 300 cells/mm3, talk to your healthcare provider about taking drugs to prevent MAC.


MedlinePlus: Clarithromycin

Drugs.com: Clarithromycin

Reviewed March 2021

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