Understanding Belsomra Side Effects

Belsomra (Suvorexant) is a prescription sleep medication that works differently from older sleeping pills. As a dual orexin receptor antagonist (DORA), it blocks wake-promoting signals in the brain rather than sedating you the way benzodiazepines or Z-drugs do. While many people tolerate Belsomra well, it's important to know what side effects are possible — and which ones need immediate medical attention.

This guide covers the most common side effects, the rare but serious ones, and practical tips for managing them.

Common Side Effects of Belsomra

Most side effects of Belsomra are mild and often improve as your body adjusts to the medication. The most frequently reported include:

• Drowsiness or next-day sleepiness: This is the most common side effect. Belsomra can make you feel groggy or sleepy the morning after taking it, especially at higher doses.
• Headache: Some people experience headaches during the first few days or weeks of treatment.
• Dizziness: Feeling lightheaded or unsteady, particularly when getting up at night or in the morning.
• Abnormal dreams: Vivid, unusual, or disturbing dreams are reported by some patients. These tend to decrease over time.
• Dry mouth: A mild but annoying side effect that usually doesn't require treatment.
• Cough and upper respiratory symptoms: Some people notice a mild cough or cold-like symptoms.
• Diarrhea: Occasional gastrointestinal upset has been reported in clinical trials.

How Common Are These Side Effects?

In clinical studies, the most frequently reported side effect was daytime drowsiness, occurring in about 7% of patients taking the 20 mg dose compared to about 3% on placebo. Most other side effects occurred in fewer than 5% of patients.

Serious Side Effects: When to Call Your Doctor

While rare, Belsomra can cause serious side effects that require immediate medical attention. Contact your doctor right away — or call 911 — if you experience any of the following:

Complex Sleep Behaviors

This is the most important safety concern with Belsomra and all sleep medications. Complex sleep behaviors include:

• Sleepwalking
• Sleep-driving (getting behind the wheel while not fully awake)
• Preparing and eating food while asleep
• Making phone calls while not fully awake
• Having sex while asleep

The FDA has issued warnings about complex sleep behaviors for all orexin receptor antagonists and other sleep medications. These behaviors can result in serious injuries or even death. If you or someone in your household notices any of these behaviors, stop taking Belsomra and contact your doctor immediately.

Sleep Paralysis

Some people experience an inability to move or speak for several minutes while falling asleep or waking up. While frightening, sleep paralysis is temporary. Tell your doctor if this happens — a dose reduction to 5 mg or 10 mg may help.

Hallucinations

Hypnagogic hallucinations (while falling asleep) or hypnopompic hallucinations (while waking up) can occur. These may include seeing, hearing, or feeling things that aren't there. Report these to your doctor.

Worsening Depression or Suicidal Thoughts

Belsomra may worsen depression in some patients. If you notice changes in mood, increased sadness, or thoughts of self-harm, contact your healthcare provider immediately. If you're in crisis, call the 988 Suicide and Crisis Lifeline by dialing 988.

Cataplexy-Like Symptoms

Rarely, Belsomra can cause sudden muscle weakness, particularly in the legs. This is more common at higher doses and should be reported to your doctor.

Impaired Next-Day Driving

Belsomra can impair your ability to drive the morning after taking it, especially at the 20 mg dose. Do not drive or operate heavy machinery until you know how Belsomra affects you. Make sure you have at least 7 hours of sleep time before driving.

Managing Common Side Effects

Here are practical tips for dealing with the most common side effects:

Next-Day Drowsiness

• Make sure you have a full 7 hours to sleep after taking Belsomra
• Start with the 10 mg dose rather than jumping to 20 mg
• Take Belsomra within 30 minutes of bedtime — don't take it too early
• Avoid alcohol, which increases drowsiness significantly
• Talk to your doctor about lowering your dose if morning grogginess persists

Headaches

• Stay hydrated throughout the day
• Over-the-counter pain relievers like acetaminophen or ibuprofen can help
• Headaches often improve within the first week or two

Abnormal Dreams

• Vivid dreams usually decrease as your body adjusts
• Avoid heavy meals, caffeine, and screen time close to bedtime
• If dreams are distressing or persistent, talk to your doctor

Dizziness

• Get up slowly from bed, especially during the night
• Keep a nightlight on to reduce fall risk
• Avoid getting up to do tasks after taking Belsomra

Side Effects and Dosage

Belsomra comes in four strengths: 5 mg, 10 mg, 15 mg, and 20 mg. Side effects tend to be dose-dependent — meaning they're more likely and more intense at higher doses. The recommended starting dose is 10 mg. Your doctor may lower you to 5 mg if side effects are bothersome or increase to 15 mg or 20 mg if the lower dose isn't effective enough.

For more on dosing, see our guide on Belsomra uses, dosage, and what you need to know.

Who Is More Likely to Experience Side Effects?

Certain groups may be more sensitive to Belsomra's effects:

• Older adults (65+): May experience more drowsiness and dizziness. Doctors typically start at 5 mg for this group.
• People taking other CNS depressants: Combining Belsomra with benzodiazepines, opioids, or alcohol increases the risk of excessive sedation. Learn more about Belsomra drug interactions.
• People with liver problems: Moderate or severe liver impairment can increase Belsomra levels in the body. Belsomra is not recommended for severe hepatic impairment.
• People taking CYP3A4 inhibitors: Certain medications (like fluconazole, diltiazem, or erythromycin) can increase Belsomra levels and worsen side effects.

Belsomra vs. Other Sleep Medications: Side Effect Comparison

One reason doctors sometimes choose Belsomra over older sleep medications is its side effect profile. Here's how it compares:

• Lower abuse potential: Compared to benzodiazepines and Z-drugs (like Ambien), Belsomra has a lower risk of dependence and abuse.
• No rebound insomnia: Many patients can stop Belsomra without the rebound insomnia that's common with other sleep aids.
• Different mechanism: Because Belsomra works on orexin receptors rather than GABA, it doesn't cause the same type of sedation or "hungover" feeling that some people get from Ambien or Lunesta.

That said, no medication is side-effect-free. For a full overview of alternatives, see our guide on alternatives to Belsomra.

When to Talk to Your Doctor

Call your doctor if:

• Side effects don't improve after the first two weeks
• You experience complex sleep behaviors of any kind
• Morning drowsiness affects your ability to drive or function
• You notice mood changes or worsening depression
• You're considering stopping Belsomra

Never stop a prescribed medication without talking to your healthcare provider first.

The Bottom Line

Belsomra is generally well-tolerated, with drowsiness, headache, and dizziness being the most common side effects. Serious side effects like sleepwalking and hallucinations are rare but require immediate medical attention. Starting at a lower dose, taking Belsomra correctly, and avoiding alcohol can help minimize side effects.

If you're ready to start Belsomra, you may need help finding a pharmacy that stocks it. Use MedFinder to check local availability, or read our guide on how to find Belsomra in stock near you.