Azithromycin (Zithromax)

What Is Azithromycin?

Azithromycin is an antibiotic drug. In the US, its brand name is Zithromax. It is sold under many other brand names in other countries, including Ultreon.

Antibiotics fight infections caused by bacteria. Azithromycin is used to fight opportunistic infections in people with HIV. Pfizer and Mack-Illert manufacture it.

Why Do People With HIV Take Azithromycin?

Azithromycin 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, and lungs. They can also be transmitted through sexual activity and cause infections in the genital area.

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." People with advanced HIV disease can get opportunistic infections. See Fact Sheet 500 for more information on Opportunistic Infections.

One opportunistic infection in people with HIV is MAC. This stands for Mycobacterium avium complex. See Fact Sheet 514 for more information on MAC. People who have a CD4 cell count of less than 50 may develop MAC.

Azithromycin is often used with another antibiotic to treat MAC. It can also be used to prevent MAC infection. If your CD4 cell count is below 50, talk to your health care provider about using azithromycin.

Azithromycin is also used to treat toxoplasmosis (see Fact Sheet 517) and cryptosporidiosis (see Fact Sheet 502).

Some people are allergic to azithromycin and similar antibiotics. Be sure to tell your health care provider if you are allergic to erythromycin or other antibiotics.

What About Drug Resistance?

Whenever you take medication, be sure to take all of the prescribed doses. Many people stop if they feel better. 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 azithromycin to fight MAC and you miss too many doses, the MAC in your body could develop resistance to azithromycin. Then you would have to take a different drug or combination of drugs to fight MAC.

How Is Azithromycin Taken?

Azithromycin is available in capsules or tablets of 250 milligram (mg). There is also a 600 mg tablet. It is also available in powder and liquid forms. To fight most infections, the dose for adults is 500 mg on the first day, and then 250 mg each day for 4 more days.

The dose used to prevent MAC infection is 1,200 mg or 1,250 mg once a week.

Azithromycin tablets can be taken with or without food. Take it with plenty of water. The capsules or liquid should be taken on an empty stomach, either 1 hour before eating or 2 hours after eating. Be sure to check the instructions carefully.

Do not take azithromycin at the same time as antacids that contain aluminum or magnesium. They will reduce the amount of azithromycin in your blood.

What Are the Side Effects?

The side effects of azithromycin mostly affect the digestive system. They include diarrhea, nausea, and pain in the abdomen. Some people get very sensitive to sunlight. Others may get headaches, be dizzy or sleepy, or have some problems hearing. Very few people who take azithromycin get these side effects. However, most anti-HIV medications also cause problems in the digestive system. Azithromycin could make those problems worse.

Some people get a severe allergic reaction to azithromycin. Let your health care provider know immediately if you get severe diarrhea, fever, joint pain, serious stomach cramps or pain, swelling in your neck, mouth, hands and feet, or trouble breathing.

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

How Does Azithromycin React With Other Drugs?

Azithromycin 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. Azithromycin probably interacts with some blood thinners, heart medications, seizure medications, and other antibiotics. Be sure your health care provider knows about all the medications and supplements you are taking.

Your health care provider may need to monitor you carefully if you are taking azithromycin and the protease inhibitor ritonavir.

Antacids with aluminum or magnesium can lower blood levels of azithromycin. Do not take antacids at the same time as azithromycin.