Azithromycin – Uses, Dosage, Side Effects, Interactions

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Azithromycin is a semi-synthetic macrolide antibiotic structurally derived from erythromycin, and a member of a subclass of macrolide antibiotics with bacteriocidal and bacteriostatic activities. It has been used in the treatment of Mycobacterium avium intracellular infections, toxoplasmosis, and cryptosporidiosis. Azithromycin reversibly binds to the 50S ribosomal subunit...

For severe symptoms, danger signs, pregnancy, child illness, or sudden worsening, seek urgent medical care.

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Article Summary

Azithromycin is a semi-synthetic macrolide antibiotic structurally derived from erythromycin, and a member of a subclass of macrolide antibiotics with bacteriocidal and bacteriostatic activities. It has been used in the treatment of Mycobacterium avium intracellular infections, toxoplasmosis, and cryptosporidiosis. Azithromycin reversibly binds to the 50S ribosomal subunit of the 70S ribosome of sensitive microorganisms, thereby inhibiting the translocation step of protein synthesis, wherein a newly synthesized peptidyl...

Key Takeaways

  • This article explains Mechanism of Action of Azithromycin in simple medical language.
  • This article explains Indications of Azithromycin in simple medical language.
  • This article explains Contraindication of Azithromycin in simple medical language.
  • This article explains Dosage of Azithromycin in simple medical language.
Educational health guideWritten for patient understanding and clinical awareness.
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Emergency safety firstUrgent warning signs are highlighted below.

Seek urgent medical care if you notice

These warning signs are general safety guidance. Local emergency numbers and clinical judgment should always come first.

  • Severe symptoms, breathing difficulty, fainting, confusion, or rapidly worsening illness.
  • New weakness, severe pain, high fever, or symptoms after a serious injury.
  • Any symptom that feels urgent, unusual, or unsafe for the patient.
1

Emergency now

Use emergency care for severe, sudden, rapidly worsening, or life-threatening symptoms.

2

See a doctor

Book a professional medical evaluation if symptoms persist, worsen, recur often, affect daily activities, or occur in a high-risk patient.

3

Learn safely

Use this article to understand possible causes, tests, treatment options, prevention, and questions to ask your clinician.

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Azithromycin is a semi-synthetic macrolide bacterial infections. সহজ বাংলা: ব্যাকটেরিয়ার সংক্রমণের ওষুধ।" data-rx-term="antibiotic" data-rx-definition="An antibiotic is a medicine used to treat bacterial infections. সহজ বাংলা: ব্যাকটেরিয়ার সংক্রমণের ওষুধ।">antibiotic structurally derived from erythromycin, and a member of a subclass of macrolide antibiotics with bacteriocidal and bacteriostatic activities. It has been used in the treatment of Mycobacterium avium intracellular infections, toxoplasmosis, and cryptosporidiosis. Azithromycin reversibly binds to the 50S ribosomal subunit of the 70S ribosome of sensitive microorganisms, thereby inhibiting the translocation step of protein synthesis, wherein a newly synthesized peptidyl tRNA molecule moves from the acceptor site on the ribosome to the peptidyl (donor) site, and consequently inhibiting RNA-dependent protein synthesis leading to cell growth inhibition and cell death. Azithromycin is an antibiotic useful for the treatment of a number of bacterial infections. This includes middle ear infections, strep throat, pneumonia, traveler’s diarrhea, and certain other intestinal infections. It may also be used for a number of sexually transmitted infections including chlamydia and gonorrhea infections.

Mechanism of Action of Azithromycin

Azithromycin binds to the 50S subunit of the 70S bacterial ribosomes and therefore inhibits RNA-dependent protein synthesis in bacterial cells.
Azithromycin usually is bacteriostatic, although the drug may be bactericidal in high concentrations against selected organisms. Bactericidal activity has been observed in vitro against Streptococcus pyogenes, S. pneumoniae, and Haemophilus influenzae. Azithromycin inhibits protein synthesis in susceptible organisms by penetrating the cell wall and binding to 50S ribosomal subunits, thereby inhibiting translocation of aminoacyl transfer-RNA and inhibiting polypeptide synthesis. The site of action of azithromycin appears to be the same as that of the macrolides (i.e., erythromycinclarithromycin), clindamycin, lincomycin, and chloramphenicol. The antimicrobial activity of azithromycin is reduced at low pH. Azithromycin concentrates in phagocytes, including polymorphonuclear leukocytes, monocytes, macrophages, and fibroblasts. Penetration of the drug into phagocytic cells is necessary for activity against intracellular pathogens (e.g., Staphylococcus aureus, Legionella pneumophila, Chlamydia trachomatis, Salmonella typhi).

Indications of Azithromycin

  • Acute bacterial sinusitis (adequately diagnosed)
  • Acute bacterial otitis media (adequately diagnosed)
  • Pharyngitis, tonsillitis
  • Acute exacerbation of chronic bronchitis (adequately diagnosed)
  • Mild to moderately severe community-acquired pneumonia
  • Skin and soft tissue infections
  • Uncomplicated Chlamydia trachomatis urethritis and cervicitis
  • Legionella Pneumonia
  • Mycoplasma Pneumonia
  • Pneumonia
  • Tonsillitis/Pharyngitis
  • Sinusitis
  • Skin and Structure Infection
  • Gonococcal Infection – Uncomplicated
  • Nongonococcal Urethritis
  • Chlamydia Infection
  • Cervicitis
  • Chancroid
  • Pelvic Inflammatory Disease
  • Chronic Obstructive Pulmonary Disease
  • Bronchitis
  • Mycobacterium avium-intracellular
  • Granuloma Inguinale
  • STD Prophylaxis
  • Pertussis Prophylaxis
  • Pertussis
  • Lyme Disease – allergy, infection, or inflammation. সহজ বাংলা: চামড়া লাল হয়ে যাওয়া।" data-rx-term="erythema" data-rx-definition="Erythema means skin redness, often from irritation, allergy, infection, or inflammation. সহজ বাংলা: চামড়া লাল হয়ে যাওয়া।">Erythema Chronicum Migrans
  • Babesiosis
  • Bacterial Endocarditis Prophylaxis
  • Toxoplasmosis
  • Campylobacter Gastroenteritis
  • Upper Respiratory Tract Infection

Contraindication of Azithromycin

  • History of severe hypersensitivity (e.g. anaphylactic reaction) to any other type of betalactam antibacterial agent (penicillins, monobactams and carbapenems).
  • Hemolytic anemia
  • Liver problems
  • Interstitial nephritis
  • Subacute cutaneous lupus erythematosus
  • Systemic lupus erythematosus
  • Allergies macl& betalactams
  • Known hypersensitivity to azithromycin, erythromycin, any macrolide or ketolide bacterial infections. সহজ বাংলা: ব্যাকটেরিয়ার সংক্রমণের ওষুধ।" data-rx-term="antibiotic" data-rx-definition="An antibiotic is a medicine used to treat bacterial infections. সহজ বাংলা: ব্যাকটেরিয়ার সংক্রমণের ওষুধ।">antibiotic. Coadministration w/ pimozide. History of cholestatic jaundice/hepatic dysfunction associated w/ prior use of azithromycin.

Dosage of Azithromycin

Strengths: 250 mg, 500 mg, 600 mg; 1 g; 2 g; 2.5 g I.V; 100 mg/5 mL; 200 mg/5 mL Suspension

Chronic Obstructive Pulmonary Disease

Immediate-release

  • 500 mg orally once a day for 3 days OR 500 mg orally as a single dose on day 1, followed by 250 mg orally once a day on days 2 to 5

Pneumonia

Immediate-release

  • 500 mg orally as a single dose on day 1, followed by 250 mg orally once a day on days 2 to 5

Extended-release

  • 2 g orally once as a single dose
  • Parenteral: 500 mg IV once a day as a single dose for at least 2 days, followed by 500 mg (immediate-release formulation) orally to complete a 7- to 10-day course of therapy

Upper Respiratory Tract Infection

ASBMT and IDSA Recommendations

Bacterial infections within the first 100 days of HCT

Immediate-release

  • Alternative treatment: 250 mg orally once a day
  • Prevention of bacterial infections for HCT patients with anticipated neutropenic periods of at least 7 days

Tonsillitis/Pharyngitis

Immediate-release

  • 500 mg orally as a single dose on day 1, followed by 250 mg orally once a day on days 2 to 5

IDSA Recommendations
Immediate-release

  • Individuals with penicillin allergy: 12 mg/kg orally once a day
  • Maximum dose: 500 mg/day
  • Duration of therapy: 5 days

 Skin and Structure Infection

Immediate-release

  • 500 mg orally as a single dose on day 1, followed by 250 mg orally once a day on days 2 to 5

IDSA and NIH Recommendations
Immediate-release

  • Patients greater than 45 kg: 500 mg orally on day 1, then 250 mg orally once a day on days 2 through 5
  • Patients less than 45 kg: 10 mg/kg orally on day 1, then 5 mg/kg orally once a day for 4 additional days
  • Alternative therapy for Bartonella infections (not endocarditis or central nervous system infections): 500 mg orally once a day for at least 3 months

Community-acquired pneumonia

Immediate-release

  • 500 mg orally as a single dose on day 1, followed by 250 mg orally once a day on days 2 to 5

Extended-release

  • 2 g orally once as a single dose
  • Parenteral: 500 mg IV once a day as a single dose for at least 2 days, followed by 500 mg (immediate-release formulation) orally to complete a 7- to 10-day course of therapy

Sinusitis

Immediate-release

  • 500 mg orally once a day for 3 days

Extended-release

  • 2 g orally once as a single dose

Pelvic Inflammatory Disease

  • 500 mg IV once a day for 1 or 2 days, followed by 250 mg (immediate-release formulation) orally once a day to complete a 7-day course of therapy.

Pediatric Pneumonia

6 months and older

Immediate-release

  • 10 mg/kg (maximum: 500 mg/dose) orally on day 1, followed by 5 mg/kg (250 mg/dose) orally once a day on days 2 to 5

Extended-release

  • Patients less than 34 kg: 60 mg/kg (maximum dose: 2 g/dose) orally as a single dose
  • Patients 34 kg or greater: 2 g orally as a single dose

16 years and older

  • Parenteral: 500 mg IV once a day as a single dose for at least 2 days, followed by 500 mg (immediate-release formulation) orally to complete a 7- to 10-day course of therapy

IDSA and Pediatric Infectious Disease Society (PIDS) Recommendations

3 months to less than 5 years

  • Parenteral: 10 mg/kg on days 1 and 2 of treatment, transitioning to oral treatment when possible
  • Oral: 10 mg/kg orally on day 1, then 5 mg/kg/day orally once a day on days 2 to 5

5 years and older

  • Oral: 10 mg/kg (maximum: 500 mg/day) orally on day 1, followed by 5 mg/kg/day
  • maximum: 250 mg/day orally on days 2 to 5

Pediatric Mycoplasma Pneumonia

6 months and older

Immediate-release

  • 10 mg/kg (maximum: 500 mg/dose) orally on day 1, followed by 5 mg/kg (250 mg/dose) orally once a day on days 2 to 5

Extended-release

  • Patients less than 34 kg: 60 mg/kg (maximum dose: 2 g/dose) orally as a single dose
  • Patients 34 kg or greater: 2 g orally as a single dose

16 years and older

  • Parenteral: 500 mg IV once a day as a single dose for at least 2 days, followed by 500 mg (immediate-release formulation) orally to complete a 7- to 10-day course of therapy

IDSA and Pediatric Infectious Disease Society (PIDS) Recommendations
3 months to less than 5 years

  • Parenteral: 10 mg/kg on days 1 and 2 of treatment, transitioning to oral treatment when possible
  • Oral: 10 mg/kg orally on day 1, then 5 mg/kg/day orally once a day on days 2 to 5

5 years and older

  • Oral: 10 mg/kg (maximum: 500 mg/day) orally on day 1, followed by 5 mg/kg/day
  • maximum: 250 mg/day orally on days 2 to 5

Tonsillitis/Pharyngitis

2 years and older

  • Immediate-release: 12 mg/kg (maximum: 500 mg/dose) orally once a day for 5 days

Pediatric, Bacterial Infection

American Academy of Pediatrics (AAP) Recommendations

Immediate-release, Less than 1 month

  • IV: 10 mg/kg IV every 24 hours
  • Oral: 10 to 20 mg/kg orally every 24 hours

1 month or older

  • Mild to moderate infections: 5 to 12 mg/kg orally once a day
  • Severe infections: 10 mg/kg IV once a day

Skin and Structure Infection

IDSA Recommendations,

Immediate-release

  • Patients greater than 45 kg: 500 mg orally on day 1, then 250 mg orally once a day on days 2 through 5
  • Patients less than 45 kg: 10 mg/kg orally on day 1, then 5 mg/kg orally once a day for 4 additional days

Side Effects of Azithromycin

Most common

More common

Rare

Drug Interactions of Azithromycin

Azithromycin may interact with the following drugs, supplements, & may change the efficacy of drugs

Pregnancy Catagory

FDA Pregnancy Category – B

Pregnancy

  • There are no adequate data on the use of azithromycin in pregnant women. In reproduction toxicity studies in animals, azithromycin was shown to pass the placenta, but no teratogenic effects were observed. The safety of azithromycin has not been confirmed with regard to the use of the active substance during pregnancy. Therefore azithromycin should only be used during pregnancy if the benefit outweighs the risk.

Lactation

  • Azithromycin has been reported to be secreted into human breast milk, but there are no adequate and well-controlled clinical studies in nursing women that have characterized the pharmacokinetics of azithromycin excretion into human breast milk. In infertility studies conducted on the rat, reduced pregnancy rates were noted following administration of azithromycin. The relevance of this finding to humans is unknown.

FAQ

 

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A simple rural-patient checklist to help you explain symptoms clearly, ask better questions, and avoid unsafe self-treatment.

Safety note: This is not a prescription or diagnosis. For severe symptoms, pregnancy danger signs, children with serious illness, chest pain, breathing difficulty, stroke-like weakness, or major injury, seek urgent care.

Which doctor may help?

Start with a registered doctor or the nearest qualified health center.

What to tell the doctor

  • Write when the problem started and how it changed.
  • Bring old prescriptions, investigation reports, and current medicines.
  • Write allergies, pregnancy status, diabetes, kidney/liver disease, and major past illnesses.
  • Bring one family member if the patient is weak, elderly, confused, or a child.

Questions to ask

  • What is the most likely cause of my symptoms?
  • Which danger signs mean I should go to hospital quickly?
  • Which tests are necessary now, and which can wait?
  • How should I take medicines safely and what side effects should I watch for?
  • When should I come for follow-up?

Tests to discuss

  • Vital signs: temperature, pulse, blood pressure, oxygen saturation
  • Basic physical examination by a clinician
  • CBC, urine test, blood sugar, or imaging only when clinically needed

Avoid these mistakes

  • Do not use antibiotics, steroid tablets/injections, or strong painkillers without proper medical advice.
  • Do not hide pregnancy, kidney disease, ulcer, allergy, or blood thinner use.
  • Do not delay emergency care when danger signs are present.

Medicine safety and first-aid guide

This section is for patient education only. It does not replace a doctor, pharmacist, or emergency care.

Safe first steps

  • Avoid heavy lifting, sudden bending, and prolonged bed rest.
  • Use comfortable posture and gentle movement as tolerated.
  • Discuss physiotherapy, X-ray, or MRI only when clinically needed.

OTC medicine safety

  • For mild back pain, pain-relief medicine may be discussed with a doctor or pharmacist.
  • Avoid repeated painkiller use if you have kidney disease, stomach ulcer, uncontrolled blood pressure, or are taking blood thinners.

Avoid these mistakes

  • Do not start antibiotics without a proper medical decision.
  • Do not use steroid tablets or injections casually for quick relief.
  • Do not delay emergency care because of home remedies.

Get urgent help if

  • Back pain with leg weakness, numbness around private area, loss of urine/stool control, fever, cancer history, or major injury needs urgent care.
Medicine names, dose, and timing must be decided by a qualified clinician or pharmacist after checking age, pregnancy, allergy, other diseases, and current medicines.

For rural patients and family caregivers

Patient health record and symptom diary

Write your symptoms, medicines already taken, test results, and questions before visiting a doctor. This note stays on your device unless you print or copy it.

Doctor to discuss: Orthopedic / spine specialist, physical medicine doctor, or qualified clinician
Tests to discuss with doctor
  • Neurological examination for leg power, sensation, reflexes, and straight leg raise
  • X-ray only if injury, deformity, long-lasting pain, or doctor suspects bone problem
  • MRI discussion if severe nerve symptoms, weakness, bladder/bowel problem, or persistent symptoms
Questions to ask
  • What is the most likely cause of my symptoms?
  • Which warning signs mean I should go to emergency care?
  • Which tests are really needed now?
  • Which medicines are safe for my age, pregnancy status, allergy, kidney/liver/stomach condition, and current medicines?
  • Is physiotherapy, posture correction, or activity modification needed?

Emergency warning signs such as chest pain, severe breathing difficulty, sudden weakness, confusion, severe dehydration, major injury, or loss of bladder/bowel control need urgent medical care. Do not wait for online information.

Safe pathway to proper treatment

Care roadmap for: Azithromycin – Uses, Dosage, Side Effects, Interactions

Use this simple roadmap to understand the next safe steps. It is educational and does not replace examination by a doctor.

Go to emergency care if you notice:
  • Severe or rapidly worsening symptoms
  • Breathing difficulty, chest pain, fainting, confusion, severe weakness, major injury, or severe dehydration
Doctor / service to discuss: Qualified healthcare provider; specialist depends on symptoms and examination.
  1. Step 1

    Check danger signs first

    If danger signs are present, seek emergency care and do not wait for online information.

  2. Step 2

    Record the symptom story

    Write when symptoms started, severity, medicines already taken, allergies, pregnancy status, and test results.

  3. Step 3

    Visit a qualified clinician

    A doctor, nurse, or qualified healthcare provider can examine you and decide which tests or treatment are needed.

  4. Step 4

    Do only useful tests

    Do tests after clinical assessment. Avoid unnecessary tests, random antibiotics, or repeated medicines without diagnosis.

  5. Step 5

    Follow up and return early if worse

    If symptoms worsen, new warning signs appear, or treatment is not helping, return for review quickly.

Rural patient practical tips
  • Take a written symptom diary and all previous prescriptions/test reports.
  • Do not hide medicines already taken, even herbal or over-the-counter medicines.
  • Ask which warning signs mean urgent referral to hospital.

This roadmap is for education. A real diagnosis and treatment plan requires history, examination, and clinical judgment.

RX Patient Help

Ask a health question safely

Write your symptom story. A health professional or site editor can review it before any answer is prepared. This box is not for emergency care.

Emergency first: Severe chest pain, breathing trouble, unconsciousness, stroke signs, severe injury, heavy bleeding, or rapidly worsening symptoms need urgent local medical care now.

Frequently Asked Questions

Is this article a replacement for a doctor?

No. It is educational content only. Patients should consult a qualified clinician for diagnosis and treatment.

When should I seek urgent care?

Seek urgent care for severe symptoms, rapidly worsening condition, breathing difficulty, severe pain, neurological changes, or any emergency warning sign.

References

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