Doctors may prescribe azithromycin, or Z-Pack, to treat strep throat in people allergic to penicillin or other first-line antibiotics. Side effects may include nausea, headaches, and diarrhea.

Strep throat is a bacterial infection that causes inflammation in the throat. Common symptoms include a sore throat, fever, and white or yellow tonsil patches.

Treatment for strep throat typically involves a 10-day course of penicillin or amoxicillin. However, if people are allergic to these antibiotics, doctors may recommend alternatives, such as azithromycin, also known as Z-Pack, Zithromax, Zmax, or Sumamed.

This article discusses the dosage, side effects, and treatment time for using Z-Pack to treat strep throat.

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Z-pack can treat strep throat and other mild to moderate infections, including:

It is a type of macrolide antibiotic, which kill the bacteria that cause infections. It will target the group A Streptococcus bacteria in people with strep throat.

However, Z-pack is not a first-line treatment for strep throat. Doctors will typically only prescribe azithromycin to people who are allergic to penicillin or other first-line antibiotics.

They will also typically recommend drinking plenty of fluids and over-the-counter (OTC) medication such as ibuprofen to help with symptoms such as pain and fever.

Z-pack is a prescription medication that typically requires a daily, single dose. The dosage for strep throat in adults is 500 milligrams (mg) on the first day and 250 mg daily for the following 4 days.

Information for taking Z-Pack includes:

  • following the dosage instructions provided by the doctor or pharmacist
  • having the medication at the same time each day
  • avoiding skipping doses or stopping the treatment early

People can take Z-Pack with or without food. However, it is important to follow the recommended dosage instructions, even if symptoms improve, before completing the entire course of medication.

Stopping the medication too early could lead to incomplete treatment and a recurrence of symptoms.

Who should not take azithromycin?

Doctors may not prescribe azithromycin for the following people:

  • someone who is allergic to Z-pack or other macrolide antibiotics
  • those with liver problems
  • children under 2 years
  • individuals who are pregnant or nursing

People should also inform their doctor about all their current medications and supplements before taking azithromycin to avoid any adverse drug interactions.

According to the United Kingdom’s National Health Service, the most common side effects of azithromycin include:

People can speak with a doctor if these side effects cause issues or do not stop after completing the course of antibiotics.

Less common side effects

Less common and more serious side effects include:

  • allergic reaction
  • severe or persistent diarrhea
  • blood or mucus in feces
  • pain in the stomach or back
  • jaundice — yellowing of the skin and eyes
  • tinnitus — ringing in the ears
  • temporary hearing loss
  • heart rhythm irregularities
  • vertigo

People experiencing severe or persistent side effects should seek immediate medical attention.

Z-Pack is generally effective in treating strep throat and relieving symptoms within a few days.

Some people may start to feel better before they finish their course of antibiotics. However, they should continue to take Z-pack as their doctor has prescribed it to prevent a recurring infection.

Doctors will prescribe a course of antibiotics to treat strep throat. According to the Centers for Disease Control and Prevention (CDC), this includes the following:

Asymptomatic people or carriers do not usually need antibiotics.

People with strep throat may choose to speak with a doctor if they experience the following symptoms:

Additionally, people who are on antibiotics and do not experience improvement within 48 hours should contact a doctor.

Azithromycin, also called Z-Pack, is a type of antibiotic doctors typically prescribe to people who are allergic to penicillin. Treatment for strep throat lasts for 5 days, though most people will start feeling better in the first couple of days.

Other treatment options for strep throat include penicillin, amoxicillin, cephalosporins, clindamycin, and clarithromycin.

People with a fever higher than 101°F (38.3°C) and symptoms of strep throat should speak with a doctor about their treatment options.