Mepolizumab: uses, dosing, side effects & brands

How mepolizumab is dosed

From the FDA label for Nucala (application BLA125526). Other mepolizumab products — different forms, different strengths — are dosed differently. Follow the label for the one you were prescribed.

Severe asthma in patients aged 12 years and older: 100 mg administered subcutaneously once every 4 weeks. ( 2.1 ) • Severe asthma in patients aged 6 to 11 years: 40 mg administered subcutaneously once every 4 weeks. ( 2.1 ) • CRSwNP: 100 mg administered subcutaneously once every 4 weeks. ( 2.1 ) • COPD: 100 mg administered subcutaneously once every 4 weeks. ( 2.1 ) • EGPA: 300 mg administered subcutaneously once every 4 weeks. ( 2.1 ) • HES: 300 mg administered subcutaneously once every 4 weeks. ( 2.1 ) 2.1 Recommended Dosage NUCALA is for subcutaneous use only, and should be injected into the upper arm, thigh, or abdomen [see Dosage and Administration ( 2.2 , 2.3 )]. Table 1. Recommended Dosage of NUCALA a 300 mg dose is administered as 3 separate 100 mg dose injections administered at least 5 cm (approximately 2 inches) apart. Indication Adults Pediatric Patients Severe asthma 100 mg every 4 weeks • 12 to 17 years of age: 100 mg every 4 weeks • 6 to 11 years of age: 40 mg every 4 weeks Chronic rhinosinusitis with nasal polyps 100 mg every 4 weeks Not applicable Chronic obstructive pulmonary disease 100 mg every 4 weeks Not applicable Eosinophilic granulomatosis with polyangiitis 300 mg a every 4 weeks Not applicable Hypereosinophilic syndrome 300 mg a every 4 weeks 12 to 17 years of age: 300 mg a every 4 weeks 2.2 Preparation and Administration of NUCALA for Injection Vial…

Mepolizumab side effects

Who shouldn’t take mepolizumab

Mepolizumab drug interactions

Mepolizumab and breastfeeding

From LactMed, the US National Library of Medicine’s Drugs and Lactation Database — quoted, not rewritten.

No information is available on the clinical use of mepolizumab during breastfeeding. Because mepolizumab is a large protein molecule with a molecular weight of 149,000 Da, the amount in milk is likely to be very low. It is also likely to be partially destroyed in the infant's gastrointestinal tract and absorption by the infant is probably minimal. A task force respiratory experts from Europe, Australia and New Zealand found that mepolizumab is possibly acceptable during breastfeeding and an international consensus panel concluded that if the patient is in agreement, and the risks and benefits have been discussed, asthma biologics can be initiated or continued while breastfeeding. Waiting for at least 2 weeks postpartum to resume therapy may minimize transfer to the infant.

National Institute of Child Health and Human Development, record revised October 15, 2024. LactMed states its information is not a substitute for professional judgement.

What people report to the FDA about mepolizumab

The FDA Adverse Event Reporting System (FAERS) collects reports from patients and clinicians. It holds 16,643 reports naming mepolizumab, and the FDA flagged 97% of those reports as serious. The effects reported most often — leaving out reports about overdose, misuse or the condition being treated, which dominate the raw list for common medicines:

• asthma5,756 reports
• dyspnoea4,550 reports
• pneumonia2,903 reports
• wheezing2,759 reports
• cough2,450 reports
• loss of personal independence in daily activities1,769 reports
• therapeutic product effect incomplete1,655 reports
• malaise1,255 reports

Source: openFDA drug/event (FAERS), retrieved September 25, 2026.

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