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Opsumit Side Effects

Generic Name: macitentan

Note: This page contains side effects data for the generic drug macitentan. It is possible that some of the dosage forms included below may not apply to the brand name Opsumit.

For the Consumer

Applies to macitentan: oral tablet

As well as its needed effects, macitentan (the active ingredient contained in Opsumit) may cause unwanted side effects that require medical attention.

Major Side Effects

If any of the following side effects occur while taking macitentan, check with your doctor immediately:

More common:
  • Decrease in the amount of urine
  • noisy, rattling breathing
  • pale skin
  • swelling of the fingers, hands, feet, or lower legs
  • troubled breathing with exertion
  • unusual bleeding or bruising
  • unusual tiredness or weakness
  • weight gain
Less common:
  • Abdominal or stomach pain or tenderness
  • clay colored stools
  • dark urine
  • difficult, burning, or painful urination
  • frequent urge to urinate
  • lower back or side pain
  • muscle aches and pains
  • difficulty with breathing
  • tightness in the chest
  • yellow eyes or skin

Minor Side Effects

Some macitentan side effects may not need any medical attention. As your body gets used to the medicine these side effects may disappear. Your health care professional may be able to help you prevent or reduce these side effects, but do check with them if any of the following side effects continue, or if you are concerned about them:

More common:
  • Chills or fever
  • cough
  • sore throat
  • stuffy or runny nose

For Healthcare Professionals

Applies to macitentan: oral tablet


The most common adverse reactions are peripheral edema, upper respiratory tract infection, nasopharyngitis, headache, anemia, and bronchitis.[Ref]


Very common (10% or more): Upper respiratory tract infection (15.3%), nasopharyngitis (14%), bronchitis (11.6%)
Common (1% to 10%): Viral respiratory tract infection, pharyngitis, sinusitis, rhinitis, lower respiratory tract infection, tracheitis, tonsillitis, rhinorrhea, productive cough, bronchial hyperreactivity
Frequency not reported: Pulmonary edema
Postmarketing reports: Nasal congestion[Ref]


Very common (10% or more): Anemia (13.2%)
Common (1% to 10%): Thrombocytopenia, hemoglobin decreased, hematocrit decreased
Frequency not reported: Decrease in mean leukocyte count, decrease in mean platelet count[Ref]


Very common (10% or more): Peripheral edema (18.2%)
Common (1% to 10%): Hypotension, flushing[Ref]

Nervous system

Very common (10% or more): Headache (13.6%)
Common (1% to 10%): Migraine[Ref]


Common (1% to 10%): Diarrhea, upper abdominal pain, gastroenteritis, abdominal pain, irritable bowel syndrome, hemorrhoids, viral gastroenteritis[Ref]


Common (1% to 10%): Urinary tract infection, metrorrhagia, menorrhagia, ovarian cyst
Frequency not reported: Adverse effects on spermatogenesis affecting male fertility[Ref]


Common (1% to 10%): Skin ulcer, pruritus, eczema, urticaria
Postmarketing reports: Angioedema, rash[Ref]


Common (1% to 10%): Arthralgia, myalgia, systemic sclerosis, costochondritis[Ref]


Common (1% to 10%): Cholelithiasis, elevated aminotransferases
Frequency not reported: Hepatotoxicity, liver failure[Ref]


Common (1% to 10%): Hypokalemia, blood urea increased[Ref]


Common (1% to 10%): Insomnia, depression[Ref]


Common (1% to 10%): Pyrexia, gynecomastia[Ref]


Common (1% to 10%): Influenza[Ref]


Common (1% to 10%): Conjunctivitis[Ref]


1. "Product Information. Opsumit (macitentan)." Actelion Pharmaceuticals US Inc, South San Francisco, CA.

2. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

3. Cerner Multum, Inc. "Australian Product Information." O 0

It is possible that some side effects of Opsumit may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.