Azithromycin

is prescribed to treat:

• Respiratory tract infections (bronchitis, pneumonia, sinusitis) • Ear infections (otitis media) • Skin and soft tissue infections • Strep throat and tonsillitis • Sexually transmitted infections (chlamydia, gonorrhea) • Mycobacterium avium complex (MAC) in HIV/AIDS patients • Pertussis (whooping cough) • Certain stomach infections (H. pylori)

It is effective against many types of bacteria.

What is ?

Azithromycin is a broad-spectrum macrolide antibiotic widely known by its brand name Zithromax or as the "Z-Pak." It is one of the most commonly prescribed antibiotics worldwide due to its effectiveness against many common bacterial infections and convenient dosing schedule.

How Does Azithromycin Work?

Azithromycin works by interfering with bacterial protein synthesis:

• Binds to the 50S ribosomal subunit of bacteria
• Inhibits bacterial protein production
• Prevents bacterial growth and reproduction (bacteriostatic)
• Can be bactericidal at higher concentrations
• Concentrates in tissues, providing extended antimicrobial activity
• Long half-life allows for once-daily dosing and shorter treatment courses

Spectrum of Activity

Azithromycin is effective against:

• Respiratory pathogens: Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Mycoplasma pneumoniae, Legionella
• Atypical bacteria: Chlamydia pneumoniae, Mycoplasma
• Sexually transmitted infections: Chlamydia trachomatis, Neisseria gonorrhoeae (increasingly resistant)
• Skin pathogens: Staphylococcus aureus (not MRSA), Streptococcus pyogenes
• Other: Mycobacterium avium complex, Bordetella pertussis

Common Uses

Respiratory Infections

Community-Acquired Pneumonia:

• Outpatient treatment for mild-moderate CAP
• Often combined with other antibiotics for hospitalized patients

Acute Bacterial Sinusitis:

• Alternative for penicillin-allergic patients
• Usually 3-5 day course

Acute Bacterial Exacerbation of COPD:

• Helps reduce symptoms and duration

Bronchitis:

• Often prescribed though most bronchitis is viral (antibiotics not helpful)

Sexually Transmitted Infections

Chlamydia:

• Single 1-gram dose is first-line treatment
• Highly effective (>95%)

Gonorrhea:

• Must be combined with ceftriaxone due to resistance
• No longer used alone for gonorrhea

Other Infections

Otitis Media (Ear Infection):

• Alternative for penicillin allergy

Strep Throat:

• Alternative for penicillin-allergic patients
• 5-day course

Skin Infections:

• Cellulitis, impetigo (uncomplicated)

MAC Prophylaxis and Treatment:

• Weekly dosing for prevention in advanced HIV/AIDS
• Part of combination therapy for active MAC

Dosage and Administration

Azithromycin dosing varies by indication:

Standard "Z-Pak" for Respiratory Infections:

• Day 1: 500 mg (two 250 mg tablets)
• Days 2-5: 250 mg once daily
• Total course: 1.5 grams over 5 days

Single Dose for Chlamydia:

• 1 gram (1000 mg) as single oral dose

Pediatric Dosing:

• Weight-based: 10-12 mg/kg once daily for 5 days
• Liquid suspension available

MAC Prophylaxis:

• 1200 mg once weekly

Administration Tips:

• Can be taken with or without food
• Take at same time each day
• Complete full course even if feeling better
• Tablets, oral suspension, and IV formulations available
• Oral suspension should be taken on empty stomach (1 hour before or 2 hours after meals)

Important Safety Information

Who Should Not Take Azithromycin?

Do not take azithromycin if you:

• Are allergic to azithromycin, erythromycin, or other macrolide antibiotics
• Are allergic to ketolide antibiotics
• Have a history of cholestatic jaundice/hepatic dysfunction with prior azithromycin use

Use with caution if you have:

• Heart rhythm problems (QT prolongation)
• Liver disease
• Kidney disease (severe)
• Myasthenia gravis
• Low potassium or magnesium levels

Drug Interactions

Medications That Increase Risk of Irregular Heart Rhythm:

• Antiarrhythmics (amiodarone, sotalol)
• Antipsychotics (haloperidol, ziprasidone)
• Antidepressants (citalopram, escitalopram)
• Methadone
• Other QT-prolonging drugs

Other Important Interactions:

• Warfarin - increased bleeding risk
• Digoxin - may increase digoxin levels
• Ergotamine - risk of ergot toxicity
• Cyclosporine, tacrolimus - may increase immunosuppressant levels
• Nelfinavir - increased azithromycin levels
• Antacids (aluminum/magnesium) - separate by 2 hours

Cardiac Safety

⚠️ Important: Azithromycin can cause QT interval prolongation, potentially leading to a rare but serious irregular heartbeat (torsades de pointes). This risk is higher in:

• Patients with existing heart rhythm problems
• Those taking other QT-prolonging medications
• Patients with low potassium or magnesium
• Elderly patients
• Those with heart disease

Inform your doctor of any heart conditions or medications.

Antibiotic Resistance

Responsible use of azithromycin:

• Only take for bacterial infections (not effective for viral infections like cold or flu)
• Complete full course even if feeling better
• Don't save antibiotics for later use
• Don't share with others
• Overuse contributes to antibiotic resistance

Monitoring

Generally minimal monitoring required:

• Most patients don't need blood tests
• If severe diarrhea develops, may test for C. difficile
• For long-term use (MAC treatment): periodic monitoring of liver function
• Monitor for signs of allergic reaction

Managing Side Effects

Gastrointestinal Upset

• Very common, especially nausea and diarrhea
• Taking with food may help (though not required)
• Usually mild and self-limited
• Stay hydrated

Diarrhea

• Most cases mild and resolve after finishing medication
• Severe or persistent diarrhea may indicate C. difficile infection (requires medical attention)
• Probiotics may help but should be separated from antibiotic by 2+ hours

Special Populations

Pregnancy:

• Category B - generally considered safe
• Used when benefits outweigh risks
• Commonly prescribed for pregnancy complications like Group B Strep colonization, chlamydia

Breastfeeding:

• Small amounts pass into breast milk
• Generally considered compatible with breastfeeding
• Monitor infant for diarrhea or thrush

Elderly:

• May be more sensitive to QT prolongation
• Dosage adjustment usually not needed
• Increased risk of C. difficile infection

Kidney Disease:

• Dosage adjustment usually not needed for mild-moderate disease
• Use caution in severe kidney disease

Liver Disease:

• Use with caution
• Contraindicated if previous liver problems with azithromycin

Advantages of Azithromycin

Convenient Dosing:

• Once-daily dosing
• Short treatment courses (often 3-5 days)
• Single-dose treatment for chlamydia
• Long tissue half-life provides extended coverage

Tolerability:

• Generally well-tolerated
• Fewer drug interactions than erythromycin
• Less GI upset than erythromycin

Efficacy:

• Broad spectrum of activity
• Effective against atypical pathogens
• High tissue concentrations

When to Contact Your Doctor

Seek immediate medical attention if you experience:

• Signs of severe allergic reaction (difficulty breathing, severe rash, swelling of face/throat)
• Irregular heartbeat, palpitations, or chest pain
• Fainting or severe dizziness
• Severe diarrhea (especially with blood or mucus)
• Severe stomach cramps
• Yellowing of skin or eyes
• Dark urine
• Unusual tiredness or weakness
• Hearing problems or ringing in ears

Contact your doctor for non-emergency issues:

• Mild to moderate diarrhea lasting more than 2 days after finishing medication
• Persistent nausea or vomiting
• New rash or itching
• Symptoms not improving after 2-3 days of treatment
• Questions about whether you need to complete the full course

Effectiveness

When used appropriately, azithromycin is highly effective:

• Chlamydia: >95% cure rate with single dose
• Community-Acquired Pneumonia: 85-95% clinical success
• Sinusitis: Comparable to other first-line antibiotics
• Strep Throat: 85-90% cure rate

Storage

• Tablets: Store at room temperature (68-77°F) in original container, protected from light and moisture
• Oral Suspension: After reconstitution, stable for 10 days at room temperature or refrigerated (do not freeze)
• Keep out of reach of children

Cost and Availability

Azithromycin is available as an affordable generic medication. The "Z-Pak" (6-tablet pack) is widely available and covered by most insurance plans. Single-dose packets for chlamydia treatment are also commonly stocked at pharmacies.

Important Reminders

• Azithromycin only treats bacterial infections
• Will not work for viral infections (colds, flu, most sore throats)
• Unnecessary use contributes to antibiotic resistance
• Complete the full prescribed course
• Don't save leftover antibiotics
• Don't share antibiotics with others

Disclaimer: This information is for educational purposes only and is not intended to replace professional medical advice, diagnosis, or treatment. Always consult your physician or other qualified healthcare provider with any questions about a medical condition or medication.