Doxepin is a tricyclic antidepressant (TCA) used, at higher doses, to treat major depressive disorder, and, at much lower doses, specifically for insomnia involving difficulty staying asleep. At higher doses it works mainly by increasing the levels of serotonin and norepinephrine in the brain; at the very low doses used for sleep, it works mainly by blocking histamine (H1) receptors, a different mechanism from its antidepressant effect. Because the depression dose and the sleep dose differ by roughly 10 to 50 times, doxepin for insomnia and doxepin for depression function almost like different treatments, even though they share the same active ingredient. Doses, contraindications, and safety information are not interchangeable between these formulations.

Doxepin carries a boxed warning, the FDA’s strictest warning, about an increased risk of suicidal thoughts and behavior in children, adolescents, and young adults taking antidepressants. Doxepin is not approved for use in children.

Doxepin at a Glance

Indications for Doxepin

• Major Depressive Disorder (MDD): Higher-dose doxepin formulations (capsules/oral solution) are used to treat depression, including low mood, fatigue, and loss of interest in daily activities.
• Insomnia: Very low-dose doxepin formulations (tablets) are used specifically for insomnia involving difficulty staying asleep, rather than for falling asleep initially.
• Anxiety: Doxepin may be used by some prescribers for anxiety-related symptoms, but this is not a universally approved indication across every doxepin formulation or country. Whether doxepin is appropriate for anxiety depends on the specific product, its approved labeling where you live, and your doctor’s clinical judgment.

Doxepin is not approved for use in children or adolescents.

How Doxepin Works

At the doses used for depression, doxepin blocks the reuptake of serotonin and norepinephrine, increasing the availability of these mood-regulating chemicals in the brain, alongside effects on other receptors that contribute to its sedative and side-effect profile.

At the very low doses used for insomnia, doxepin works mainly by blocking histamine (H1) receptors, producing a sedating effect without the same degree of anticholinergic and heart-related effects seen at higher, antidepressant doses.

Dosage and Administration

Doxepin dosing differs substantially depending on what it is being used for, and the depression dose and the insomnia dose are not interchangeable. This information is general and does not replace individualized guidance from your doctor.

For depression (higher-dose formulations):

• Typical adult treatment is generally in the 75–150 mg/day range.
• Treatment is generally started lower and increased gradually.
• The maximum may be up to 300 mg/day when clinically necessary and appropriately monitored.
• Older adults are usually started at lower doses.

For insomnia (very low-dose formulations):

• 6 mg once daily for adults.
• 3 mg once daily for adults 65 years and older.
• Take within 30 minutes before bedtime.
• Have at least 7 hours available for sleep before you need to be awake again.
• Do not take within 3 hours of a meal.

Doxepin should not be discontinued abruptly, as this may lead to withdrawal-like symptoms; your doctor will generally reduce the dose gradually when stopping. Do not change your dose or stop treatment on your own.

Overdose risk: Like other tricyclic antidepressants, doxepin particularly at the higher doses used for depression can be dangerous and potentially fatal in overdose, including serious cardiac effects. Doctors typically prescribe limited quantities where clinically appropriate. Keep this medicine out of reach of others, and seek emergency care immediately for a suspected overdose.

Common Side Effects

Common/expected effects:

• Drowsiness (particularly at higher, antidepressant doses; also expected at the low insomnia dose, though usually milder)
• Dry mouth, constipation, and blurred vision
• Weight or appetite changes
• Dizziness or a drop in blood pressure on standing (orthostatic effects), especially at higher doses and in older adults

Serious symptoms requiring urgent medical attention (these are not common, but you should know what to watch for):

• New or worsening suicidal thoughts or behavior, particularly in patients under 25, when starting treatment, or after a dose change. Antidepressant treatment can be associated with this risk. Seek medical help promptly for these or for major mood or behavior changes.
• Serotonin syndrome: a potentially serious reaction that can occur when doxepin is combined with other serotonergic medicines (see Drug Interactions). Symptoms include agitation, confusion, rapid heart rate, high blood pressure, dilated pupils, muscle twitching, sweating, tremor, and, in severe cases, high fever. Seek urgent care if these occur.
• Heart rhythm changes, such as a fast or irregular heartbeat, more relevant at higher doses.
• Abnormal sleep-related behaviors, such as sleep-walking or engaging in complex behaviors while not fully awake, and abnormal thinking or hallucinations. Contact your doctor promptly if these occur.
• Signs of a severe allergic reaction, such as swelling of the face or throat, or difficulty breathing.

Not every side effect listed here is common report any unusual symptoms to your doctor promptly.

Contraindications

Formal contraindications for doxepin generally include:

• Known hypersensitivity (allergy) to doxepin or relevant product components
• Use of an MAOI, or use within the required interval (generally 14 days) before or after stopping one, because of the risk of serotonin syndrome or a severe reaction
• Untreated narrow-angle glaucoma, as applicable to the specific formulation
• Current or past urinary retention, as applicable to the specific formulation

Exact contraindication wording can differ slightly between doxepin products and regions, so always check the label of your specific product or ask your pharmacist.

Recent heart attack and unstable heart disease are situations calling for careful medical assessment and caution — since tricyclic antidepressants can affect cardiac conduction and heart rhythm — rather than being a formal contraindication in every applicable product label. Doctors weigh this carefully, especially in older adults or those with existing heart problems.

Effects on Pregnancy, Breastfeeding, Liver, and Kidneys

• Pregnancy: Human pregnancy data on doxepin are limited. It should be used during pregnancy only if the potential benefit justifies the potential risk. If you are pregnant or planning pregnancy, discuss this with your doctor rather than stopping or changing an antidepressant on your own — untreated depression also carries risks to you and a pregnancy.
• Breastfeeding: Doxepin and/or its metabolites can pass into breast milk, and significant adverse effects have been reported in breastfed infants. Other medicines may generally be preferred during breastfeeding, particularly for newborn or preterm infants. Discuss your feeding and treatment options with your doctor rather than stopping a prescribed medicine on your own.
• Liver: Doxepin is metabolized primarily in the liver. Liver impairment may affect how the body handles doxepin, and your doctor may use additional caution, closer monitoring, or dose adjustments depending on your individual situation and the specific product.
• Kidneys: Since doxepin is metabolized mainly in the liver, kidney disease may still call for additional clinical consideration or monitoring depending on the formulation and your individual circumstances, though a universal kidney-based dose adjustment is not established for every product.

Drug Interactions

• MAOIs: Must not be combined with doxepin, and doxepin should generally not be started within 14 days of stopping an MAOI, because of the risk of serotonin syndrome or a severe reaction (see Contraindications).
• Other serotonergic medicines: Combining doxepin with other medicines that affect serotonin may increase the risk of serotonin syndrome. Not every combination carries the same level of risk. Representative examples include SSRIs, SNRIs, other TCAs, triptans, certain opioids, lithium, buspirone, and St. John’s Wort. Tell your doctor about all of these before starting doxepin.
• Medicines that raise doxepin levels: Certain drugs that inhibit an enzyme called CYP2D6 — such as fluoxetine, paroxetine, bupropion, quinidine, and terbinafine — can increase doxepin exposure and the risk of side effects. Your doctor may adjust your dose or monitor you more closely if you need one of these medicines; do not stop or avoid a prescribed medicine on your own without discussing it with your doctor.
• Alcohol and other CNS depressants: Alcohol, benzodiazepines, opioids, sedating antihistamines, and other sedating medicines can add to doxepin’s drowsiness and impair alertness, coordination, and judgment. For the low-dose insomnia formulation in particular, alcohol should generally be avoided because of additive central nervous system effects.

Tell your doctor or pharmacist about all prescription and over-the-counter medicines, supplements, and herbal products you use, since this list is not complete.

A Note for Insomnia Use: Sleep Apnea

Low-dose doxepin used for insomnia is ordinarily not recommended in patients with severe sleep apnea. Tell your doctor if you have sleep apnea or other significant breathing problems during sleep before starting this medicine.

Popular Brand Names: India and US

• India: Doxin (verify current availability with your pharmacy)
• US: Silenor (low-dose insomnia tablets), Sinequan (higher-dose capsules/oral solution) verify current availability, as brand marketing can change over time

Approximate Price in India

Doxin 25 mg capsules, strip of 10: approximately ₹55–₹85 per strip, based on current online pharmacy listings.

Prices may vary by brand, strength, formulation, pack size, pharmacy, location, and available discounts.

How HealthPil Can Help

If you’re struggling with depression, anxiety, or insomnia, talking to a qualified doctor can help you understand your options. Through HealthPil, you can consult a doctor about your symptoms and questions about doxepin and other treatments. Medicines should be started, adjusted, or stopped only under the guidance of a qualified healthcare professional.