Effectiveness of Danazol for Long-term Prophylaxis in Hereditary Angioedema

Efficacy of Danazol

Danazol significantly reduces both the frequency and severity of hereditary angioedema (HAE) attacks, including potentially life-threatening laryngeal attacks, as demonstrated by double-blind, randomized controlled trials 1, 2
At high doses, danazol is effective in more than 90% of patients with HAE, reducing attack frequency by more than 90% in most patients 1

The dose of danazol should be adjusted to the lowest possible amount that provides effective control of attacks, with typical dosing ranges from 100 mg on alternate days to up to 600 mg per day, depending on individual patient requirements 1, 4
Dose adjustments should not occur more frequently than once per week, as the beneficial effects of danazol accrue slowly 4, 5

Common side effects of danazol include weight gain, acne, virilization, menstrual irregularities, hirsutism, hepatic abnormalities, growth retardation, behavioral and mood alterations, headache, and cardiovascular risk 1
Side effects are dose-related and more common at doses higher than 200 mg per day 1

The American Academy of Allergy, Asthma, and Immunology recommends that danazol be considered a second-line option for long-term prophylaxis due to its side effect profile 1, 2, 6
First-line prophylactic treatments are now subcutaneous C1-INH and lanadelumab due to their superior safety profiles, as recommended by the American Academy of Allergy, Asthma, and Immunology 1, 2, 4
Every patient should be evaluated for long-term prophylaxis based on attack frequency, severity, location, access to acute care, comorbid conditions, and patient preference, according to the American Academy of Allergy, Asthma, and Immunology 4, 6

In resource-limited settings where first-line treatments are not available, the risk-benefit ratio may favor greater use of danazol despite its side effect profile, as suggested by the World Allergy Organization 1, 3
Danazol is contraindicated during pregnancy due to potential masculinizing effects on the female fetus, as stated by the American College of Obstetricians and Gynecologists 7, 6