Common use
Sinequan, the brand name for doxepin, is a tricyclic antidepressant (TCA) used to treat major depressive disorder and anxiety disorders. By influencing norepinephrine and serotonin signaling, it can help alleviate persistent low mood, excessive worry, tension, sleep disturbance, and somatic symptoms associated with depression and anxiety. Clinicians often consider Sinequan when selective serotonin reuptake inhibitors (SSRIs) or serotonin–norepinephrine reuptake inhibitors (SNRIs) are not effective or not well tolerated.
At very low doses, doxepin also has sedating antihistamine properties. A specialized low-dose formulation is FDA-approved for sleep maintenance insomnia in adults, helping reduce awakenings during the night. Some clinicians may use low-dose doxepin off-label for chronic pruritus (itch) or urticaria due to its H1 antihistamine effects. Regardless of the indication, the goal is to use the lowest effective dose for the shortest necessary duration while monitoring for side effects.
Dosage and direction
For depression or anxiety in adults, Sinequan is typically started low and titrated slowly. A common initial dose is 25–50 mg once daily at bedtime (or divided 2–3 times daily if daytime sedation is acceptable), with gradual increases every few days as tolerated. Usual effective ranges are 75–150 mg per day for outpatients. Some patients with severe symptoms may require higher doses under close supervision; inpatient maximums can reach 300 mg/day. Because Sinequan is sedating, many patients take most or all of the dose at night.
For sleep maintenance insomnia, specialized low-dose doxepin (3–6 mg) is taken once within 30 minutes of bedtime, not within 3 hours of a meal to reduce next-day drowsiness. Do not combine low-dose sleep formulations with higher antidepressant/anxiolytic doses of doxepin unless specifically directed by a clinician.
Older adults, people with liver impairment, and those sensitive to side effects should start at even lower doses (e.g., 10–25 mg at night for mood/anxiety, or 3 mg for insomnia) and titrate cautiously. Never change your dose or stop Sinequan abruptly without medical guidance; dose reductions are typically gradual to prevent withdrawal-like symptoms such as nausea, headache, irritability, or sleep disruption.
Precautions
Antidepressants carry a boxed warning for increased risk of suicidal thoughts and behaviors in children, adolescents, and young adults, especially during initiation and dose changes. Close monitoring is essential for all patients early in treatment and after adjustments. Report worsening mood, agitation, panic, irritability, or unusual behavior changes promptly.
Sinequan can cause significant drowsiness, dizziness, and impaired coordination. Avoid driving or operating machinery until you know how it affects you. Alcohol and other sedative drugs increase these effects and should be avoided. Due to anticholinergic properties, Sinequan may cause dry mouth, constipation, blurred vision, urinary retention, and confusion—risks that are higher in older adults.
Use caution if you have cardiovascular disease (arrhythmias, conduction abnormalities, recent myocardial infarction), seizure disorders, bipolar disorder (risk of inducing mania/hypomania), glaucoma (especially narrow-angle), urinary retention, hyperthyroidism, or hepatic impairment. Doxepin can rarely prolong the QT interval; discuss risks if you take other QT-prolonging drugs, have electrolyte abnormalities, or a history of long QT syndrome.
Pregnancy and lactation: Use only if benefits outweigh risks. Doxepin is excreted in breast milk and may cause sedation in infants; discuss alternatives with your clinician. Pediatric use for depression/anxiety is not routine with TCAs; specialized care is required.
Contraindications
Do not use Sinequan if you have hypersensitivity to doxepin, other tricyclic antidepressants, or dibenzoxepin derivatives. It is contraindicated with monoamine oxidase inhibitors (MAOIs) or within 14 days of stopping an MAOI; serious and potentially fatal reactions can occur. Sinequan is also contraindicated in patients with untreated narrow-angle glaucoma or urinary retention due to strong anticholinergic effects. Avoid use immediately after a recent myocardial infarction unless a cardiologist advises otherwise.
Possible side effects
Common side effects: drowsiness, dizziness, dry mouth, constipation, blurred vision, increased appetite, weight gain, nausea, sweating, and tremor. Many of these improve as your body adjusts or with dose changes. Hydration, sugar-free lozenges or gum for dry mouth, fiber-rich diet for constipation, and taking the dose at bedtime can help.
Less common but important reactions include orthostatic hypotension (lightheadedness on standing), confusion (especially in older adults), urinary retention, sexual dysfunction, and photosensitivity. Rare but serious side effects include arrhythmias, seizures, severe constipation/ileus, jaundice or liver enzyme elevations, severe allergic reactions, angle-closure glaucoma, and blood dyscrasias. Serotonin syndrome is possible when combined with other serotonergic agents; symptoms include agitation, restlessness, sweating, rapid heartbeat, tremor, muscle rigidity, and fever—seek urgent care if suspected.
Contact your clinician promptly if you experience worsening depression, unusual behavior changes, suicidal thoughts, chest pain, fainting, palpitations, severe constipation, yellowing of the skin/eyes, or vision changes (eye pain, halos). In emergencies, call local emergency services.
Drug interactions
Do not use Sinequan with MAOIs (e.g., phenelzine, tranylcypromine) or within 14 days of MAOI discontinuation due to risk of hypertensive crisis and serotonin toxicity. Avoid combining with linezolid or IV methylene blue unless benefits outweigh risks and close monitoring is in place.
CYP2D6 inhibitors such as fluoxetine, paroxetine, quinidine, terbinafine, and bupropion can increase doxepin levels and side effects; dose adjustments and monitoring may be required. Cimetidine can raise TCA concentrations. Conversely, enzyme inducers (e.g., carbamazepine) may lower doxepin levels, reducing efficacy.
Concomitant serotonergic agents (SSRIs, SNRIs, trazodone, triptans) increase serotonin syndrome risk; use cautiously and monitor. Additive sedation occurs with alcohol, benzodiazepines, opioids, sedating antihistamines, cannabis, and other CNS depressants. Anticholinergic burden increases with medications like oxybutynin, diphenhydramine, and some antipsychotics.
Doxepin may reduce the efficacy of certain antihypertensives (e.g., guanethidine) and can potentiate blood pressure drops with clonidine. Caution with QT-prolonging drugs (certain antipsychotics, macrolide antibiotics, methadone). Always provide your clinician and pharmacist a complete medication, supplement, and herbal list, including St John’s wort, to check for interactions.
Missed dose
If you miss a dose for depression or anxiety and remember within a few hours, take it as soon as possible. If it is close to the next dose, skip the missed dose and resume your regular schedule. Do not double up. For low-dose sleep formulations, skip the dose if you cannot allow a full night’s sleep or if it is too late in the night—taking it late can cause next-day drowsiness. Consistency supports stable symptom control; consider reminders or pill organizers.
Overdose
Tricyclic antidepressant overdose is a medical emergency. Symptoms can include profound drowsiness, confusion, agitation, seizures, fast or irregular heartbeat, low blood pressure, widened QRS on ECG, difficulty breathing, and coma. If an overdose is suspected, call emergency services immediately. Do not wait for symptoms to worsen. In a medical setting, clinicians provide airway support, cardiac monitoring, and targeted treatments to stabilize heart rhythm and blood pressure. Early care is critical for the best outcomes.
Storage
Store Sinequan at room temperature (68–77°F or 20–25°C) in a dry place away from moisture and light. Keep the bottle tightly closed and out of reach of children and pets. Do not store in the bathroom. Dispose of unused or expired medication according to pharmacist or local take-back program instructions. Never share prescription medications with others.
U.S. Sale and Prescription Policy
In the United States, Sinequan (doxepin) is a prescription-only medication. It is unsafe and unlawful to obtain prescription drugs without a valid prescription from a licensed clinician. Any source that offers to sell Sinequan without a prescription should be avoided for your safety and to remain compliant with federal and state regulations.
Surgery Center of Pottsville provides a legal and structured pathway to access Sinequan: schedule a clinician-led evaluation to determine whether doxepin is appropriate for your condition. If indicated, a licensed prescriber will issue a prescription to your preferred local or mail-order pharmacy. Services include medication counseling, interaction screening, dosage optimization, and follow-up to ensure safety and effectiveness. This approach keeps your care compliant, evidence-based, and personalized—no shortcuts or unsupervised medication use.
If you are considering treatment with Sinequan for depression, anxiety, or sleep maintenance insomnia, contact the Surgery Center of Pottsville to book a consultation. You will receive a thorough assessment, a discussion of alternatives, and—when appropriate—a prescription sent directly to a trusted pharmacy, along with ongoing support to monitor outcomes and manage side effects.
