Why Drug Interactions Matter With Belsomra

Belsomra (Suvorexant) is processed by your liver using a specific enzyme called CYP3A4. Many common medications also use or affect this same enzyme. When other drugs slow down CYP3A4, Belsomra can build up to dangerous levels in your body. When other drugs speed up CYP3A4, Belsomra may not work as well.

On top of that, because Belsomra affects your central nervous system (CNS), combining it with other CNS depressants can cause excessive drowsiness, breathing problems, or impaired functioning.

This guide covers the most important Belsomra drug interactions — what's completely off-limits, what requires caution, and what to tell your doctor.

Contraindicated: Medications You Must NOT Take With Belsomra

The following medications are contraindicated with Belsomra — meaning they should never be used together. These are all strong CYP3A4 inhibitors that prevent your body from properly breaking down Belsomra:

• Ketoconazole (antifungal)
• Itraconazole (antifungal)
• Posaconazole (antifungal)
• Clarithromycin (antibiotic)
• Telithromycin (antibiotic)
• Nefazodone (antidepressant)
• Ritonavir (HIV medication)
• Saquinavir (HIV medication)
• Nelfinavir (HIV medication)
• Indinavir (HIV medication)
• Boceprevir (hepatitis C medication)
• Telaprevir (hepatitis C medication)
• Conivaptan (used for low sodium levels)

If you take any of these medications, do not take Belsomra. Tell your doctor immediately. They will need to prescribe a different sleep medication or find an alternative for the interacting drug.

Use With Caution: Moderate CYP3A4 Inhibitors

These medications don't completely block CYP3A4, but they slow it down enough to increase Belsomra levels in your body. If you take any of these, your doctor should reduce your Belsomra dose to 5 mg:

• Fluconazole (antifungal — commonly prescribed for yeast infections)
• Erythromycin (antibiotic)
• Diltiazem (heart/blood pressure medication)
• Verapamil (heart/blood pressure medication)
• Grapefruit juice (yes, it's a moderate CYP3A4 inhibitor — more on this below)

If you've been prescribed any of these and you're already taking Belsomra, don't stop either medication on your own. Talk to your doctor about adjusting your Belsomra dose.

Medications That May Reduce Belsomra's Effectiveness

Strong CYP3A4 inducers speed up the enzyme that breaks down Belsomra, potentially making it less effective. These include:

• Rifampin (antibiotic used for tuberculosis)
• Carbamazepine (seizure/mood stabilizer, brand name Tegretol)
• Phenytoin (seizure medication, brand name Dilantin)

If you take any of these, Belsomra may not work well enough to help you sleep. Your doctor may need to consider a different sleep medication altogether.

CNS Depressants: Increased Sedation Risk

Combining Belsomra with other medications that slow down the central nervous system increases the risk of excessive drowsiness, impaired coordination, slowed breathing, and difficulty thinking clearly. Be cautious with:

• Benzodiazepines (Xanax, Ativan, Klonopin, Valium)
• Opioid pain medications (oxycodone, hydrocodone, morphine, fentanyl, tramadol)
• Tricyclic antidepressants (amitriptyline, nortriptyline)
• Other sleep medications (Ambien, Lunesta, trazodone)
• Antihistamines (diphenhydramine/Benadryl, doxylamine/Unisom)
• Muscle relaxants (cyclobenzaprine, baclofen)
• Anti-anxiety medications

This doesn't necessarily mean you can't take these with Belsomra, but your doctor needs to know about all of them to weigh the risks and adjust doses if necessary.

Alcohol and Belsomra

Do not drink alcohol while taking Belsomra. Alcohol is a CNS depressant that significantly increases the sedative effects of Belsomra. Combining the two can cause:

• Extreme drowsiness
• Dangerously impaired coordination and judgment
• Increased risk of complex sleep behaviors (sleepwalking, sleep-driving)
• Slowed breathing

Even a single alcoholic drink in the evening can intensify Belsomra's effects. If you drink regularly, make sure your doctor knows before starting Belsomra.

Food Interactions

Grapefruit and Grapefruit Juice

Grapefruit is a moderate CYP3A4 inhibitor, which means it can increase Belsomra levels in your body. If you regularly drink grapefruit juice or eat grapefruit, tell your doctor. They may need to lower your Belsomra dose to 5 mg.

High-Fat Meals

Taking Belsomra with or right after a heavy, high-fat meal can delay how quickly it starts working. For best results, take Belsomra on an empty stomach or after a light snack.

Caffeine

While not a direct drug interaction, caffeine (from coffee, tea, energy drinks, or chocolate) is a stimulant that can reduce Belsomra's effectiveness. Avoid caffeine in the afternoon and evening.

Digoxin

If you take digoxin (a heart medication), your doctor should monitor your digoxin levels when starting Belsomra. Suvorexant can increase digoxin levels in the body, which may lead to side effects from digoxin.

What to Tell Your Doctor Before Starting Belsomra

Before your doctor prescribes Belsomra, make sure they know about:

1. Every medication you take — prescription and over-the-counter, including pain relievers, allergy medications, and cold medicines
2. All supplements and herbal products — some herbal supplements (like St. John's Wort) can affect CYP3A4
3. Your alcohol use — be honest about how often and how much you drink
4. Any history of narcolepsy — Belsomra is contraindicated in narcolepsy
5. Liver problems — hepatic impairment can affect how your body processes Belsomra
6. Depression or mental health conditions — Belsomra may worsen depression

Keeping an updated medication list on your phone is a simple habit that can prevent dangerous interactions. Show it to every provider who prescribes you a new medication.

What If You're Already Taking an Interacting Medication?

If you discover that one of your current medications interacts with Belsomra:

• Don't stop either medication without talking to your doctor first
• Call your doctor or pharmacist to discuss the interaction and next steps
• Your doctor may adjust your Belsomra dose, switch you to a different sleep medication, or find an alternative for the interacting drug

Your pharmacist is an excellent resource for catching drug interactions. They review your full medication profile every time you fill a prescription and can flag potential problems your doctor may have missed.

Quick Reference: Belsomra Interaction Categories

• Never combine: Strong CYP3A4 inhibitors (ketoconazole, ritonavir, clarithromycin, etc.)
• Dose reduction needed: Moderate CYP3A4 inhibitors (fluconazole, diltiazem, verapamil, grapefruit juice)
• May reduce effectiveness: Strong CYP3A4 inducers (rifampin, carbamazepine, phenytoin)
• Increased sedation risk: CNS depressants (benzodiazepines, opioids, alcohol, antihistamines)
• Monitor levels: Digoxin

The Bottom Line

Belsomra is generally safe when taken as directed, but its reliance on the CYP3A4 enzyme for metabolism means it has significant interactions with many common medications. The most important rule: never take Belsomra with strong CYP3A4 inhibitors. Always give your doctor and pharmacist a complete list of everything you take.

For more on Belsomra's side effects, read our side effects guide. And if you need help finding Belsomra at a pharmacy near you, try MedFinder.