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Zithromax Patient Tips

Written by C. Fookes, BPharm on Jul 10, 2017.

How it works

  • Zithromax is a brand (trade) name for azithromycin.
  • Azithromycin is a type of antibiotic, called a macrolide. It kills bacteria by inhibiting bacterial protein synthesis.
  • Azithromycin is used to treat infections caused by susceptible bacteria such as Mycobacterium avium, M. intracellulare, and Chlamydia trachomatis.


  • Used to treat infections caused due to susceptible bacteria that occur on the skin, in the lungs, in the ears.
  • Also, treats some sexually transmitted infections.
  • Used specifically for the treatment and prevention of mycobacterium avium complex (a type of respiratory infection) in people with advanced HIV. May be used in addition to other antibiotics.
  • Active against a wide range of microorganisms and shows good penetration into human tissue. Some bacteria may be resistant (not killed by Zithromax).
  • May be better tolerated and have more effective tissue penetration than other similar antibiotics such as erythromycin.
  • Can be dosed once daily which improves adherence.
  • May be used to treat bacterial infections in people intolerant of penicillins.


If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:

  • Nausea, diarrhea, vomiting, abdominal pain, dyspepsia, flatulence, fatigue, headache are some of the more common side effects.
  • Liver damage and may affect liver function, sometimes fatally. Must be discontinued if any signs of liver dysfunction occur.
  • May cause changes in the way the heart beats, resulting in the development of cardiac arrhythmias. The risk is greater in people with a history of QT prolongation, on other drugs known to prolong the QT interval, with low levels of potassium or magnesium in their blood, and in those receiving anti-arrhythmic agents such as sotalol, amiodarone, and procainamide.
  • Severe diarrhea is a potential side effect of almost all antibacterial agents, including Zithromax.
  • May cause severe skin reactions and photosensitivity (increased sensitivity to sunlight). Discontinue Zithromax and seek urgent medical advice should a rash develop.
  • May interact with some other medications including warfarin and nelfinavir.
  • Dosage may need decreasing in those with renal disease and may not be suitable for people with myasthenia gravis.

Notes: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. For a complete list of all side effects, click here.

Bottom Line

Zithromax is an antibiotic used to treat a variety of different infections and appears to have better tissue penetration and tolerability to similar antibiotics such as erythromycin. It has the distinct advantage of once-daily dosing; however, diarrhea is a common side effect.


  • May be taken with or without food; however, zithromax tablets may be better tolerated if taken with food.
  • Do not take at the same time as aluminum or magnesium-containing antacids.
  • Discontinue Zithromax immediately and seek urgent medical advice if any sign of an allergic reaction (such as a rash or difficulty breathing) occurs.
  • Take exactly as directed and finish the course as prescribed by your doctor, even if you feel better beforehand. Skipping doses or not completing treatment can decrease the effectiveness of the treatment and promote the development of resistance.
  • Although diarrhea is common with Zithromax, contact your doctor if you develop severe diarrhea especially if it is very watery or contains blood. Sometimes diarrhea may occur one to two months after starting Zithromax.
  • Contact your doctor immediately if you develop any signs of liver disease such as yellowing of the skin or whites of the eyes, upper right abdominal pain, rash, clay-colored stools, severe nausea, and vomiting.
  • If you are allergic to other macrolides (such as clarithromycin, erythromycin, or telithromycin) do not take Zithromax. Also, avoid Zithromax if you have taken it before and it caused damage to your liver.
  • Take Zithromax oral suspension immediately after reconstituting. Do not store for later use.
  • Avoid excessive exposure to sunlight or tanning beds. Use an SPF 30 or higher sunblock when outside and wear protective clothing as Zithromax can make you sunburn more easily.

Response and Effectiveness

  • Takes between two and a half to just over three hours for peak concentrations to be reached. A loading dose (a higher than normal starting dose) may be used to reach steady concentrations sooner.
  • Can be dosed once daily.
  • May take several days before symptoms of the infection start to abate. Always finish the course as prescribed.


Zithromax (azithromycin) [Package Insert]. Revised 04/2017. Pfizer Laboratories Div Pfizer Inc

  • Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Zithromax only for the indication prescribed.
  • Disclaimer: Every effort has been made to ensure that this information is accurate, up-to-date, and complete, but no guarantee is made to that effect. Drug information contained herein may be time sensitive. This drug information does not endorse drugs, diagnose patients or recommend therapy. It is an informational resource designed as a supplement to, and not a substitute for, the expertise, skill, knowledge and judgment of healthcare practitioners. The absence of a warning for a given drug or drug combination in no way should be construed to indicate that the drug or drug combination is safe, effective or appropriate for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of this information. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the drugs you are taking, check with your doctor, nurse or pharmacist.

Copyright 1996-2018 Revision Date: 2017-07-10 01:30:03