What is the recommended treatment for whooping cough (pertussis)?

Treatment of Whooping Cough (Pertussis)

Azithromycin is the first-line antibiotic for treating pertussis across all age groups, with a 5-day course being as effective as traditional 14-day erythromycin regimens while causing significantly fewer gastrointestinal side effects. 1

Antibiotic Selection and Dosing

First-Line Treatment: Azithromycin

Azithromycin is the preferred agent due to superior tolerability, shorter treatment duration, and equal efficacy compared to erythromycin. 1, 2

Age-Specific Dosing:

• Infants <1 month: 10 mg/kg/day for 5 days (preferred over erythromycin due to significantly lower risk of infantile hypertrophic pyloric stenosis) 1
• Infants 1-5 months: 10 mg/kg/day for 5 days 1
• Infants ≥6 months and children: 10 mg/kg (max 500 mg) on day 1, then 5 mg/kg/day (max 250 mg) on days 2-5 1
• Adults: 500 mg on day 1, then 250 mg daily on days 2-5 1

Alternative First-Line: Clarithromycin

• Infants 1-5 months: 15 mg/kg/day divided into two doses for 7 days 1
• Children and adults: 7.5 mg/kg twice daily (adults: 500 mg twice daily) for 7 days 1

Second-Line: Erythromycin

Erythromycin should be avoided in infants <1 month due to association with infantile hypertrophic pyloric stenosis (IHPS). 1, 3 If erythromycin must be used:

• Children: 40-50 mg/kg/day in divided doses for 14 days 1, 3
• Adults: 500 mg every 6 hours or 250 mg every 12 hours for 14 days 3

Alternative for Macrolide Contraindications

• Trimethoprim-sulfamethoxazole (TMP-SMZ): For patients >2 months with macrolide allergies or contraindications 1

Timing of Treatment: Critical for Effectiveness

Start antibiotics immediately upon clinical suspicion without waiting for culture confirmation. 1

Treatment Effectiveness by Disease Stage:

• Catarrhal phase (first 2 weeks): Antibiotics rapidly clear B. pertussis from the nasopharynx, decrease coughing paroxysms, and reduce complications 1
• Paroxysmal phase (>3 weeks): Limited clinical benefit for symptom control, but treatment still indicated to prevent transmission 1
• Key point: Antibiotics eliminate the organism and render patients non-infectious but do not alter the clinical course once paroxysmal cough is established 4, 2

Isolation Requirements

Isolate patients at home and away from work/school for 5 days after starting antibiotics to prevent transmission. 1 Pertussis has a secondary attack rate exceeding 80% among susceptible persons. 1

Important Medication Considerations

Azithromycin-Specific Precautions:

• Do not administer with aluminum- or magnesium-containing antacids (reduces absorption) 1
• Use with caution in patients with impaired hepatic function 1

Erythromycin-Specific Warnings:

• Contraindicated in infants <1 month due to IHPS risk 1
• Inhibits cytochrome P450 enzymes; monitor for drug interactions with digoxin, triazolam, ergot alkaloids 1
• Significantly higher gastrointestinal side effects (41% vs 19% with azithromycin) 2

Post-Exposure Prophylaxis

The same antibiotic regimens and doses used for treatment are recommended for post-exposure prophylaxis. 1, 5

Who Should Receive Prophylaxis:

• All household contacts regardless of vaccination status 5, 6
• High-risk contacts: Infants <12 months (especially <4 months), pregnant women in third trimester 1, 5
• Healthcare workers with known exposure 1

Timing:

• Administer within 21 days of exposure for effectiveness 6
• Prophylaxis aims to eradicate B. pertussis from the nasopharynx of infected persons (symptomatic or asymptomatic) 6

Therapies That Do NOT Work

Do not use β-agonists, antihistamines, corticosteroids, or pertussis immunoglobulin—these have no proven benefit in controlling coughing paroxysms. 1

Common Pitfalls to Avoid

• Waiting for culture confirmation before starting treatment: This delays therapy during the critical catarrhal phase when antibiotics are most effective 1
• Using erythromycin in young infants: The IHPS risk makes azithromycin strongly preferred in infants <6 months 1
• Expecting symptom improvement with late treatment: Once paroxysmal cough is established, antibiotics prevent transmission but don't improve symptoms 1, 4
• Poor compliance with erythromycin: Only 55% of patients complete the 14-day course vs 90% completing 5-day azithromycin 2
• Forgetting prophylaxis for household contacts: Creates a protective "cocoon" around vulnerable infants 5