Medication guide

Suvorexant (Belsomra)

What is suvorexant?

Suvorexant is known as Belsomra in the United States and Japan alike (ベルソムラ on Japanese packaging). It's a newer type of sleep medicine called an orexin receptor antagonist: instead of sedating the whole brain, it turns down orexin, the brain's "stay awake" signal, letting natural sleep take over.

How is it different from other sleeping pills?

Dependence and tolerance are unlikely: far less habit-forming than older sleeping pills, and it keeps working without needing higher doses
Works with your sleep system, not against it: it dims the wake signal rather than sedating you
Helps with both falling asleep and staying asleep
Not a controlled substance: no special import limits, and simpler prescribing rules than older sleeping pills

What is it used for in Japan?

Insomnia: both falling asleep and staying asleep.

What it targets: the whole night. By dimming the wake signal, it helps with getting to sleep and with staying asleep through the night.

How does it help?

By quieting the brain's wake signal at night, it makes it easier both to fall asleep and to stay asleep. It works from the first nights, though sleep often continues to improve as your rhythm recovers. It works best alongside good sleep habits, as support while sleep finds its feet again.

What should I tell my doctor before starting?

A few situations rule it out entirely; your doctor will choose something else if any of these apply:

A past allergic reaction to suvorexant
Certain antifungals, antibiotics, and antivirals (such as itraconazole, clarithromycin, ritonavir, and the COVID treatment Paxlovid); the combination isn't allowed, so always tell us your full medication list, including short courses

And tell your doctor first if any of these apply; these usually just need adjustments or a closer eye:

Heart or blood pressure medicines like diltiazem or verapamil; the dose is kept lower with these
Other sedating medicines, or regular alcohol use
Breathing problems during sleep (such as sleep apnea)
Pregnant, planning to be, or breastfeeding (see the section below)

How do I take it?

Once a night, right before bed, and only on nights you can give a full night to sleep.

Take it immediately before lying down; avoid taking it with or right after a meal, which can delay the effect
If you forget it, just skip that night. Never take a second dose in one night
Go easy on alcohol; it adds to the drowsiness
Older adults are usually prescribed a lower dose

What side effects should I expect?

Most are mild. Not everyone gets them.

Sleepiness carrying into the next morning: the main one; if it happens, tell us, and don't drive while drowsy
Headache
Tiredness
Vivid dreams or nightmares in some people

If anything is bothering you, tell your doctor; there's often a way to adjust.

Finally, one thing that is rare (most people never experience it) but good to know:

A brief feeling of being unable to move while falling asleep or waking (sleep paralysis), or dream-like impressions at the edge of sleep. Harmless but startling; tell us and the plan can be adjusted

Will I become dependent? How do I stop safely?

Unlikely; this is where suvorexant differs from older sleeping pills. Dependence and tolerance are unlikely with this class, it keeps working without needing higher doses, and there's no craving. Stopping is usually simple: many people use it for a period while sleep recovers, then step off with their doctor. As always, make changes together rather than alone, so the timing is right.

Can I drive while taking it?

No. Don't drive after taking it, and be alert to leftover drowsiness the next morning. Like other sleep medicines, the Japanese label instructs that patients on suvorexant shouldn't drive or operate dangerous machinery, because the effect can carry into the next day. If morning sleepiness keeps happening, tell your doctor; the dose or the medicine can be changed.

What about pregnancy and breastfeeding?

Tell your doctor early; this is decided case by case. In pregnancy, sleep medicines are kept to the minimum and other approaches are often preferred first; with breastfeeding, the decision is individual. Don't start, stop, or continue on your own. Our guides to medication in pregnancy and medication while breastfeeding cover the wider picture.