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Opsumit Side Effects Center

Medical Editor: John P. Cunha, DO, FACOEP

Last reviewed on RxList 5/6/2015

Opsumit (macitentan) is an endothelin receptor antagonist used to treat pulmonary arterial hypertension (PAH, WHO Group I) to delay disease progression. Common side effects of Opsumit include low red blood cell count (anemia), common cold-like symptoms (stuffy nose or sore throat), bronchitis, headache, flu and urinary tract infection.

The recommended dosage of Opsumit is 10 mg once daily for oral administration. Opsumit may interact with rifampin, ketoconazole, and ritonavir. Tell your doctor all medications and supplements you use. Opsumit is not recommended for use during pregnancy. It may harm a fetus. Women can receive the drug only through the Opsumit Risk Evaluation and Mitigation Strategy (REMS) Program and must comply with applicable pregnancy testing and contraception requirements before initiating treatment; consult your doctor. Consult your doctor before breastfeeding.

Our Opsumit (macitentan) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What is Prescribing information?

The FDA package insert formatted in easy-to-find categories for health professionals and clinicians.

Opsumit FDA Prescribing Information: Side Effects
(Adverse Reactions)


Clinically significant adverse reactions that appear in other sections of the labeling include:

Clinical Trial Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice.

Safety data for OPSUMIT were obtained primarily from one placebo-controlled clinical study in 742 patients with PAH (SERAPHIN study) [see Clinical Studies]. The exposure to OPSUMIT in this trial was up to 3.6 years with a median exposure of about 2 years (N=542 for 1 year; N=429 for 2 years; and N=98 for more than 3 years). The overall incidence of treatment discontinuations because of adverse events was similar across OPSUMIT 10 mg and placebo treatment groups (approximately 11%).

Table 2 presents adverse reactions more frequent on OPSUMIT than on placebo by ≥ 3%.

Table 2 : Adverse Reactions

Adverse Reaction OPSUMIT 10 mg
(N=242) (%)
(N=249) (%)
Anemia 13 3
Nasopharyngitis/pharyngitis 20 13
Bronchitis 12 6
Headache 14 9
Influenza 6 2
Urinary tract infection 9 6

Postmarketing Experience

The following adverse reactions have been identified during postapproval use of OPSUMIT. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

Immune system disorders: hypersensitivity reactions (angioedema, pruritus and rash)

Respiratory, thoracic and mediastinal disorders: nasal congestion

General disorders and administration site conditions: edema/fluid retention. Cases of edema and fluid retention occurred within weeks of starting Opsumit, some requiring intervention with a diuretic, fluid management or hospitalization for decompensated heart failure.

Cardiac disorders: symptomatic hypotension

Read the entire FDA prescribing information for Opsumit (Macitentan Tablets)

Report Problems to the Food and Drug Administration


You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

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