Doxepin: what it treats, how to take it, side effects
Last updated September 3, 2026.
Doxepin is a tricyclic antidepressant - it increases the amounts of certain natural substances in the brain needed for mental balance. You may know it as Sinequan. The tricyclics are the original antidepressants - older, sedating, and still genuinely useful. (A separate low-dose doxepin tablet exists for insomnia; this page covers the depression and anxiety use.)
What does it treat?
Depression and anxiety. The full effect takes several weeks or longer - the early weeks are the investment, not the verdict.
How do you take it?
Capsule or liquid concentrate one to three times daily, with or without food, same time(s) daily. The concentrate: measure with the special marked dropper and dilute in 4 ounces of water, milk, or orange, grapefruit, tomato, prune, or pineapple juice just before taking - never carbonated drinks. Continue even when you feel well; never stop suddenly - the exit is a gradual dose decrease under your doctor. Missed dose: take it when you remember unless the next one is close; never double up.
Side effects to know
- Common: nausea, vomiting, weakness or tiredness, dizziness, enlarged pupils, dry mouth, mouth sores, sun sensitivity - sunscreen joins the routine - flushing, appetite or weight changes, taste changes, indigestion, constipation, diarrhea, difficulty urinating, excessive thirst and urination, ringing in the ears, and sex-drive changes.
- Serious - call your doctor immediately: the tricyclic alarm set - fainting, seizures, fast or irregular heartbeat, chest pain, yellowing of skin or eyes, fever and sore throat, unusual bleeding or bruising, severe muscle stiffness, confusion, and hallucinations.
- Mood watch - the antidepressant class warning: especially at the start and around dose changes, depression can deepen or suicidal thinking can emerge - new or worsening depression, agitation, panic, sleeplessness, irritability, acting without thinking, or any thought of self-harm gets called in the same day, and family should know the list too. If you or someone you love is in crisis, call or text 988 - the Suicide and Crisis Lifeline - any time.
Who should not take it?
Anyone who has taken an MAO inhibitor in the past 14 days - the combination is dangerous. Flag glaucoma, difficulty urinating or prostate issues, heart-rhythm problems, and bipolar disorder history - a tricyclic can flip bipolar into mania. Children are not normally given doxepin. It is sedating: no driving until you know your response, and alcohol multiplies the sedation. If you become pregnant, call your doctor.
When is it an emergency?
Fainting, a seizure, chest pain with a racing heart, or confusion with hallucinations is a 911 call. Tricyclic overdose is dangerous - any suspected extra doses go straight to Poison Control at 1-800-222-1222 or 911. Pymander's escalation routing is built and tested specifically for this class of decision; see the safety architecture working paper.
What a Pymander AI doctor consult looks like
Illustrative example, not a real member's messages.
Common questions
Why does doxepin take weeks to work?
Tricyclics shift brain chemistry gradually - MedlinePlus says the full effect can take several weeks or longer. The sedating and dry-mouth effects arrive immediately; the antidepressant effect lags behind. This gap is why the early weeks carry the closest mood watch and why "continue even when you feel well" - and equally, do not quit at week two because nothing has happened - are the standing instructions.
What is the mood warning about?
The antidepressant class warning: a small number of people, especially under 25, develop increased suicidal thinking on antidepressants - concentrated at the start of treatment and around dose changes. MedlinePlus lists the watch-for set: new or worsening depression, agitation, panic, insomnia, irritability, impulsivity, severe restlessness, and any thought of self-harm. Family or a caregiver should know the list. Same-day call to your doctor for any of them; crisis is 988, call or text, any time.
Why can't I just stop doxepin?
Tricyclics create physical dependence: stopping suddenly brings withdrawal - nausea, headache, malaise, and a fast mood crash that mimics relapse. MedlinePlus: your doctor will probably want to decrease your dose gradually. The taper is the exit, and it is uneventful when done on schedule. Feeling better is the reason to plan a taper with your doctor, not to stop on your own.
Why did my doctor ask about MAO inhibitors?
Tricyclics plus MAO inhibitors - or a tricyclic within 14 days of stopping one - can trigger a dangerous reaction: high fever, rigidity, blood-pressure swings. The washout runs both directions. Every prescriber and your pharmacist needs the complete list - doxepin has enough interactions that the list is a safety device.
How is doxepin different from an SSRI?
Generation and texture: tricyclics are older, broader in brain targets - hence the dry mouth, constipation, sedation, and urinary effects - while SSRIs are cleaner but can carry their own set. Doxepin still earns its place: for depression with insomnia or anxiety in the mix, the sedation is a feature at night. It is also generic and inexpensive. Overdose is the real differentiator: tricyclics are dangerous in overdose, which is why supply and storage deserve care.
What happens if I miss a dose of doxepin?
Take it as soon as you remember, unless it is almost time for the next one - then skip it and never double up. If you take it at night and remember at noon, the practical move is usually to wait for the evening dose - doubling sedating doses is the scenario to avoid. The nightly anchor is the habit to protect.