Silenor Side Effects: What to Expect and When to Call Your Doctor

Silenor (doxepin 3 mg and 6 mg) has one of the more favorable side effect profiles among sleep medications — particularly at the low doses approved for insomnia. But like all medications, it's not side-effect free. Here's what you should know before you start taking it.

Common Side Effects of Silenor

In clinical trials involving 1,017 patients, approximately 1% withdrew from the study due to side effects — one of the lowest discontinuation rates among insomnia medications. The most commonly reported side effects include:

Drowsiness or somnolence — The most common side effect. Usually occurs during the night while you're sleeping; next-day drowsiness is possible if you don't get a full 7–8 hours of sleep.

Nausea — Reported in some patients, particularly when first starting the medication.

Upper respiratory tract infection (in clinical trial reporting) — Occurred at similar rates to placebo groups.

Dizziness — Particularly if you get up quickly during the night.

Importantly, at the 3–6 mg insomnia doses, Silenor does NOT typically cause the anticholinergic side effects associated with higher-dose doxepin (depression doses). This means dry mouth, constipation, confusion, blurred vision, and urinary retention are rare at therapeutic insomnia doses.

Next-Day Drowsiness: What You Need to Know

Silenor has a half-life of about 15 hours, meaning it stays in your system throughout the following day. Most patients do not experience next-day impairment at the recommended 3–6 mg doses — but these factors increase the risk:

Taking it within 3 hours of eating (food increases and prolongs absorption)

Getting fewer than 7–8 hours of sleep after taking it

Combining it with alcohol or other sedating medications

Taking the 6 mg dose (the 3 mg dose has a lower sedation profile)

Serious Side Effects: When to Call Your Doctor Immediately

While rare, some serious side effects require prompt medical attention:

Complex sleep behaviors (sleep-driving, sleep-eating, making phone calls while asleep) — If you or someone in your household notices you doing things during the night that you don't remember, stop Silenor and contact your doctor immediately. This is more likely if you combine Silenor with alcohol or other CNS depressants.

Worsening of depression or thoughts of self-harm — Silenor carries a boxed warning (the FDA's strongest warning) for increased risk of suicidal thoughts in children, adolescents, and young adults up to age 24. Contact your doctor right away if depression worsens or you have any new or unusual thoughts about self-harm. Silenor is not approved for patients under 12.

Signs of severe allergic reaction — Rash, hives, swelling of the face or throat, difficulty breathing. Seek emergency care immediately.

Urinary retention or difficulty urinating — More likely in older men or patients with prostate issues. Contact your doctor if you notice this.

Signs of angle-closure glaucoma — Eye pain, seeing halos around lights, sudden vision changes. Silenor is contraindicated in untreated narrow-angle glaucoma.

Side Effects in Older Adults

Older adults (65+) may be more sensitive to the sedating effects of doxepin. Doctors typically start elderly patients at the lower 3 mg dose. The American Geriatrics Society flags doxepin as potentially inappropriate in patients 65+ at doses above 6 mg, but at the 3–6 mg insomnia dose, the risk profile is often acceptable — especially compared to alternatives like benzodiazepines or Z-drugs.

Is Silenor Habit-Forming?

No. Silenor is not a controlled substance and has no known dependence or addiction potential. Clinical studies of up to 3 months showed no rebound insomnia or withdrawal symptoms when the medication was stopped. This is a key advantage over benzodiazepines and Z-drugs.

Tips to Minimize Side Effects

Take Silenor within 30 minutes of bedtime, not within 3 hours of eating

Plan to stay in bed for at least 7–8 hours after taking it

Avoid alcohol the night you take it

Do not drive or operate heavy machinery until you know how the medication affects you

Start at 3 mg if you're 65 or older

For information on drug interactions with Silenor, see: Silenor Drug Interactions: What to Avoid and What to Tell Your Doctor.

If you're struggling to find Silenor at a pharmacy near you, medfinder can help locate a pharmacy that has it in stock.