Azithromycin is a widely-used antibiotic in the macrolide class, often prescribed for various diseases. Always consult a healthcare professional before starting, stopping, or modifying any medication or treatment plan. This article is intended for informational purposes only and should not be considered medical advice.

  1. Medical Uses

Azithromycin is primarily used to treat a wide range of bacterial infections, including respiratory tract infections, skin infections, sexually transmitted diseases, and ear infections. Some of the common conditions treated with azithromycin include:

  • Streptococcal pharyngitis (strep throat)
  • Pneumonia
  • Acute bacterial sinusitis
  • Chlamydia trachomatis
  • Mycoplasma pneumonia
  • Haemophilus influenza
  1. Bacterial Susceptibility

Azithromycin is effective against various Gram-positive and Gram-negative bacteria and some atypical bacteria. It works by inhibiting bacterial protein synthesis, leading to cell death. However, some bacteria have resisted azithromycin due to the overuse and misuse of antibiotics. To ensure the continued efficacy of azithromycin, it is crucial to prescribe and use the drug responsibly.

  1. Pregnancy and Breastfeeding

Azithromycin is classified as a Category B drug by the U.S. Food and Drug Administration (FDA), meaning it is generally considered safe for use during pregnancy. However, it should only be used when the potential benefits outweigh the risks. Research has shown that azithromycin does pass into breast milk in small amounts. While no adverse effects have been reported in nursing infants, it is essential to consult a healthcare professional before using azithromycin during pregnancy or breastfeeding.

  1. Airway Diseases

Azithromycin has effectively treated chronic inflammatory airway diseases like bronchiectasis and cystic fibrosis. Its anti-inflammatory properties help reduce airway inflammation and improve lung function. Moreover, its long half-life allows for once-daily dosing, making it a convenient option for patients with chronic respiratory conditions.

  1. Adverse Effects

Common side effects include gastrointestinal issues like nausea, vomiting, diarrhoea, and abdominal pain. Less common side effects may include headache, dizziness, and rash. Serious side effects, although rare, can include allergic reactions, liver dysfunction, and QT interval prolongation, which may lead to potentially fatal heart arrhythmias. Contact your healthcare provider immediately if you experience severe or persistent side effects.

  1. Pharmacology

6.1 Mechanism of Action

It works by binding to the 50S ribosomal subunit of susceptible bacteria, inhibiting protein synthesis and preventing bacterial growth. Its broad-spectrum activity allows it to target a wide range of bacteria, including both Gram-positive and Gram-negative species.

6.2 Pharmacokinetics

Azithromycin is well-absorbed after oral administration and has a bioavailability of approximately 38%. Its extensive tissue distribution allows it to effectively penetrate and accumulate within cells, particularly in the lungs and sinuses. It has a long half-life of 68 hours, which usually allows for once-daily dosing.

  1. History

Azithromycin was first discovered in 1980 by researchers at the pharmaceutical company Pliva. It was later developed

in collaboration with Pfizer and introduced to the market under the Zithromax brand in 1991. Since then, it has become one of the most commonly prescribed antibiotics worldwide, with millions of prescriptions issued each year.

  1. Society and Culture Subsection

8.1 Available Forms

Azithromycin is available in various forms, including tablets, capsules, oral suspensions, and intravenous (IV) solutions. The appropriate form and dosage depend on the specific infection being treated and the patient’s age, weight, and medical history.

8.2 Usage

Azithromycin is prescribed for both acute and chronic bacterial infections. It is essential to follow the healthcare provider’s instructions and complete the entire course of treatment, even if symptoms improve before the medication is finished. Failure to complete the entire course can contribute to antibiotic resistance.

A healthcare provider administers azithromycin in injectable form intravenously (IV).

Take azithromycin in all other dosage forms precisely as directed.

For the liquid and tablet regular suspensions:

Take a glass of water once daily, with or without meals.
If it irritates your stomach, take it with meals.

For the liquid extended-release suspension:

On an empty stomach, only take one dose (at least 1 hour before or 2 hours after a meal).

When using eye drops:

One drop is injected into the afflicted eye twice daily for the first two days.
Once daily over the following five days, one drop is injected into the afflicted eye.

Take the missing dosage as soon as you recall if you forget to take it. Skip the missed dosage if it is almost time for the next one, and take your next dose as scheduled. Never take two azithromycin doses at the same time.


A healthcare provider administers azithromycin in injectable form intravenously (IV).

Take any further dosages of azithromycin precisely as directed by your physician. Pay close attention to the instructions on your medication label.

Based on the kind of infection and the patient’s age, your doctor will decide on the optimal dose for you or your kid.

Regarding the capsules and joint suspension:

Adults: For the majority of infections, a dose of 250, 500, or 600 mg of azithromycin should be taken once a day in this form. For less severe infections, azithromycin may be used for a more extended period—up to 10 days. One or two grams of medication are recommended for various infections.
Children: The dosage for this type of azithromycin in children ranges from 5 mg to 20 mg per kilogram of body weight per day, depending on weight. Typically, azithromycin is used for 3 to 5 days.

For the suspensions with an extended-release:

Adults: A single 2 g dosage of azithromycin in this form should be administered.
Children: This version of azithromycin should be administered as a single dosage of 60 mg/kg (or 27 mg/lb) body weight to children six months of age and older. Children who weigh 75 lb (34 kg) or more should take 2 grams for adults.

When using eye drops:

For the first two days, administering one drop of azithromycin eye drops twice a day, eight to twelve hours apart, to the afflicted eye or eyes is advised. The injured eye or eyes should receive one drop daily for five days.

If you are allergic to azithromycin, erythromycin, or any other macrolide drug


  1. Research

Research continues to expand our understanding of its potential applications in treating various infections and conditions. Ongoing studies explore its role in managing other chronic inflammatory diseases, preventing bacterial infections in high-risk populations, and evaluating its efficacy in combination with other medications.

  1. COVID-19

During the COVID-19 pandemic, it gained attention as a potential treatment option for patients with the novel coronavirus. Early observational studies suggested that azithromycin, combined with hydroxychloroquine, might positively affect COVID-19 patient outcomes. However, subsequent larger, controlled trials found no significant benefit of using it for COVID-19 treatment. As a result, the World Health Organization (WHO) and other health authorities currently do not recommend azithromycin for COVID-19 treatment outside of clinical trials.


Serious side effects have been reported with azithromycin, including:

Hypersensitivity reaction: An allergic reaction to azithromycin is possible. Tell your healthcare provider right away if you have some or all of the following symptoms of an allergic reaction:

hives or rash
difficulty breathing or swallowing

Azithromycin should not be used for extended periods. Prolonged use can lead to the growth of dangerous organisms resistant to azithromycin. Take it for the duration prescribed by your doctor.

Clostridium difficile-associated diarrhoea: Azithromycin and other antibiotics can kill the “good” bacteria in the colon, leading to C. difficile bacteria. C. difficile is a “bad” bacteria that can cause diarrhoea.
Heart rhythm changes: Azithromycin can cause abnormal changes in the heart’s electrical activity that may lead to a potentially life-threatening irregular heart rhythm. Tell your doctor if you have a history of any of the following:

existing heart rhythm problems called QT prolongation
low blood levels of potassium or magnesium
slower than average heart rate
use of drugs for the treatment of abnormal heart rhythms or arrhythmias

Muscle problems: Azithromycin can worsen the symptoms of a muscle disease called myasthenia gravis. In addition, azithromycin can cause muscle weakness. Alert your doctor if you have a history of myasthenia gravis or experience new muscle weakness.

Do not take azithromycin if you:

Are allergic to azithromycin, erythromycin, or any other macrolide antibiotic


Azithromycin is a versatile and widely-used antibiotic with a broad spectrum of activity against various bacterial infections. Its efficacy in treating respiratory, skin, and sexually transmitted infections has made it a popular choice among healthcare professionals. Understanding its pharmacology, potential side effects, and proper usage is crucial for ensuring its continued effectiveness in combating bacterial infections.

While azithromycin has demonstrated potential in treating certain airway diseases due to its anti-inflammatory properties, its role in treating COVID-19 remains uncertain, with current guidelines not recommending its use outside clinical trials. Ongoing research will continue to explore new applications and potential benefits of azithromycin in the fight against infectious diseases.



  1. Peters DH, Friedel HA, McTavish D. Azithromycin. A review of its antimicrobial activity, pharmacokinetic properties, and clinical efficacy. Drugs 1992;44:750-99.
  2. Foulds G, Shepard RM, Johnson RB. The pharmacokinetics of azithromycin in human serum and tissues. J Antimicrob Chemother 1990;25 Suppl A:73-82.
  3. Mandell LA, Wunderink RG, Anzueto A, et al. Infectious Diseases Society of America/American Thoracic Society consensus guidelines on managing community-acquired pneumonia in adults. Clin Infect Dis 2007;44 Suppl 2:S27-72.
  4. Tran DH, Sugamata R, Hirose T, et al. Azithromycin, a 15-membered macrolide antibiotic, inhibits influenza A(H1N1)pdm09 virus infection by interfering with the virus internalization process. J Antibiot (Tokyo) 2019;72:759-68.
  5. Gautret P, Lagier JC, Parola P, et al. Hydroxychloroquine and azithromycin as a treatment of COVID-19: results of an open-label non-randomized clinical trial. Int J Antimicrob Agents 2020;56:105949.
  6. WHO. Therapeutics and COVID-19: a living guideline. World Health Organization, 2021. Available at: (accessed on DATE).
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Tanzir Islam Britto

Hello, I'm Dr. Tanzir Islam Britto. As a dedicated physician, I've embarked on my medical journey at Bangabandhu Sheikh Mujib Medical College (BSMMC), previously known as Faridpur Medical College, where I pursued my Bachelor of Medicine and Bachelor of Surgery (MBBS). I completed my degree at Shahabuddin Medical College (SMC). Alongside my medical career, I am an amateur writer and an active social media advocate, where I share insights into health, wellness, and more.

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