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Belsomra Side Effects

Generic name: suvorexant

Medically reviewed by Philip Thornton, DipPharm. Last updated on Aug 15, 2022.

Note: This document contains side effect information about suvorexant. Some dosage forms listed on this page may not apply to the brand name Belsomra.


Common side effects of Belsomra include: drowsiness. Continue reading for a comprehensive list of adverse effects.

Applies to suvorexant: oral tablet.

Serious side effects of Belsomra

Along with its needed effects, suvorexant (the active ingredient contained in Belsomra) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking suvorexant:

More common

  • Sleepiness or unusual drowsiness

Less common

  • Unusual or abnormal dreams

Incidence not known

  • Changes in behavior
  • discouragement
  • fear or nervousness
  • feeling sad or empty
  • irritability
  • lack of appetite
  • loss of interest or pleasure
  • loss of memory
  • problems with memory
  • seeing, hearing, or feeling things that are not there
  • temporary inability to move or talk for up to several minutes while you are going to sleep or wake up
  • temporary weakness in your legs
  • thoughts of killing oneself
  • tiredness
  • trouble concentrating

Other side effects of Belsomra

Some side effects of suvorexant may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

Less common

For Healthcare Professionals

Applies to suvorexant: oral tablet.


The most common adverse reaction was somnolence.[Ref]


Common (1% to 10%): Diarrhea, dry mouth[Ref]

Nervous system

Common (1% to 10%): Headache, somnolence, dizziness[Ref]


Common (1% to 10%): Abnormal dreams[Ref]


Common (1% to 10%): Cough, upper respiratory tract infection[Ref]


1. "Product Information. Belsomra (suvorexant)." Merck & Company Inc (2014):

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.