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Sinequan Side Effects

Generic Name: doxepin

Note: This page contains side effects data for the generic drug doxepin. It is possible that some of the dosage forms included below may not apply to the brand name Sinequan.

For the Consumer

Applies to doxepin: oral capsule, oral solution, oral tablet

As well as its needed effects, doxepin (the active ingredient contained in Sinequan) may cause unwanted side effects that require medical attention.

Major Side Effects

If any of the following side effects occur while taking doxepin, check with your doctor immediately:

Incidence not known:
  • Abdominal or stomach pain
  • agitation
  • black, tarry stools
  • bleeding gums
  • blood in the urine or stools
  • blurred vision
  • burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
  • canker sores
  • chest pain
  • chills
  • clay-colored stools
  • cold sweats
  • confusion about identity, place, and time
  • convulsions
  • cool, pale skin
  • cough or hoarseness
  • dark urine
  • decrease in the frequency of urination
  • decrease in urine volume
  • decreased urine output
  • depression
  • difficulty in passing urine (dribbling)
  • difficulty with breathing
  • difficulty with speaking
  • dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
  • drooling
  • dry mouth
  • fast, pounding, or irregular heartbeat or pulse
  • feeling of warmth
  • fever
  • flushed, dry skin
  • fruit-like breath odor
  • general feeling of tiredness or weakness
  • headache
  • hearing loss
  • hostility
  • increased hunger
  • increased thirst
  • increased urination
  • irritability
  • itching or rash
  • lethargy
  • lip smacking or puckering
  • loss of appetite
  • loss of balance control
  • loss of bladder control
  • lower back or side pain
  • mood or mental changes
  • muscle spasm or jerking of all extremities
  • muscle trembling, jerking, or stiffness
  • muscle twitching
  • nausea
  • nervousness
  • nightmares
  • noisy breathing
  • painful or difficult urination
  • pinpoint red spots on the skin
  • pounding in the ears
  • puffing of the cheeks
  • rapid or worm-like movements of the tongue
  • rapid weight gain
  • redness of the face, neck, arms, and occasionally, upper chest
  • restlessness
  • ringing or buzzing or other unexplained noise in the ears that continues
  • seeing, hearing, or feeling things that are not there
  • seizures
  • shakiness and unsteady walk
  • shakiness in the legs, arms, hands, or feet
  • shuffling walk
  • sore throat
  • sores, ulcers, or white spots on the lips, tongue, or in the mouth
  • slurred speech
  • stiffness of the limbs
  • stupor
  • sudden loss of consciousness
  • sweating
  • swelling of the face, ankles, or hands
  • swollen glands
  • tightness in the chest
  • troubled breathing
  • twisting movements of the body
  • uncontrolled chewing movements
  • uncontrolled movements, especially of the arms, face, legs, neck, and back
  • unexplained weight loss
  • unpleasant breath odor
  • unsteadiness, trembling, or other problems with muscle control or coordination
  • unusual bleeding or bruising
  • unusual tiredness or weakness
  • vomiting of blood
  • yellow eyes or skin

If any of the following symptoms of overdose occur while taking doxepin, get emergency help immediately:

Symptoms of overdose:
  • Clumsiness
  • disturbed concentration
  • drowsiness
  • enlarged pupils
  • increased or excessive unconscious or jerking movements
  • low body temperature
  • muscle aches
  • muscle weakness
  • shivering
  • sleepiness
  • weak or feeble pulse
  • weight gain

Minor Side Effects

Some doxepin side effects may not need any medical attention. As your body gets used to the medicine these side effects may disappear. Your health care professional may be able to help you prevent or reduce these side effects, but do check with them if any of the following side effects continue, or if you are concerned about them:

Incidence not known:
  • Change in taste or bad, unusual or unpleasant (after) taste
  • decreased interest in sexual intercourse
  • diarrhea
  • difficulty having a bowel movement (stool)
  • enlargement of the breasts
  • gas in the stomach
  • hair loss or thinning of the hair
  • heartburn
  • inability to have or keep an erection
  • increased in sexual ability, desire, drive, or performance
  • increased interest in sexual intercourse
  • increased sensitivity of the skin to sunlight
  • loss in sexual ability, desire, drive, or performance
  • redness or other discoloration of the skin
  • severe sunburn
  • swelling of the breasts or breast soreness in both females and males
  • swelling of the testicles
  • unexpected or excess milk flow from breasts
  • weight loss

For Healthcare Professionals

Applies to doxepin: oral capsule, oral concentrate, oral tablet

Nervous system

Nervous system side effects have been reported more frequently with drowsiness as the most cited adverse effect. Dystonia, myoclonus, worsening of seizure control, hoarseness, aphonia, visual hallucinations, and tinnitus have also been reported. Mania can occur and is a particular risk in patients with bipolar disease.[Ref]


Anticholinergic side effects have been reported frequently and include blurry vision, dry mouth, constipation and urinary retention.[Ref]

Although doxepin is not addicting, withdrawal symptoms after abrupt discontinuation may occur and include hypertension, tachycardia, restlessness, abdominal distress and emesis. A case of doxepin withdrawal mania has also been reported.[Ref]


Gastrointestinal side effects have included constipation and dry mouth and less frequently nausea and vomiting.[Ref]

A study of 26,005 antidepressant users has reported 2.3 times more upper GI bleeding episodes with the use of non-SSRI's. Upper gastrointestinal tract bleeding was observed in 2.0 times more frequently in patients receiving doxepin.[Ref]


Cardiovascular side effects have included orthostatic hypotension, tachycardia, syncope, intracardiac conduction blocks, and ventricular arrhythmias. Torsades de pointes tachycardia has been reported in a woman who swallowed 6 g of doxepin (the active ingredient contained in Sinequan) in an attempt to commit suicide.[Ref]

The incidence of orthostatic hypotension is thought to be higher with doxepin than with other tricyclic antidepressants. Both antiarrhythmic and proarrhythmic effects have been reported in association with doxepin therapy, however, the incidence of proarrhythmic effects may be lower with doxepin than other tricyclic antidepressants. Caution, however, should be exercised if doxepin must be used in patients with cardiovascular disease.[Ref]


A retrospective register study of the World Health Organization (WHO) database for spontaneous reporting of adverse drug reactions (n=668) suggests that the risk of hyponatremia during treatment with antidepressants seems to be highest in women, in the elderly, during the summer season, and during the first weeks of therapy.[Ref]

Endocrine side effects have included hyperprolactinemia and hyponatremia (in association with the syndrome of inappropriate secretion of antidiuretic hormone).[Ref]


Oncologic side effects have included a case of breast cancer occurring in a male taking doxepin (the active ingredient contained in Sinequan) [Ref]


Hematologic side effects have included immune hemolytic anemia and thrombocytopenia.[Ref]


General side effects commonly reported have included weight gain. Anorexia has also been reported.[Ref]


Hepatic side effects have included induction of cholestatic and hepatic reactions generally related to idiosyncratic hypersensitivity associated with the use of tricyclic antidepressants. Although these have generally been mild, severe injuries with fulminant hepatitis have been reported. A single case report has suggested that doxepin (the active ingredient contained in Sinequan) may induce recurrent acute hepatitis.[Ref]


1. Norman TR, Judd F, Holwill BJ, Burrows GD "Doxepin and visual hallucinations." Aust N Z J Psychiatry 16 (1982): 295-6

2. Golden RN, Evans DL, Nau CH, Jr "Doxepin and tinnitus." South Med J 76 (1983): 1204-5

3. Lee HK "Dystonic reactions to amitriptyline and doxepin ." Am J Psychiatry 145 (1988): 649

4. Lippmann S, Moskovitz R, O'Tuama L "Tricyclic-induced myoclonus." Am J Psychiatry 134 (1977): 90-1

5. Rhoads JM, Lowell SH, Hedgepeth EM "Hoarseness and aphonia as a side effect of tricyclic antidepressants." Am J Psychiatry 136 (1979): 1599

6. Ayd FJ, Jr "Long-term treatment of chronic depression: 15-year experience with doxepin HCl." J Clin Psychiatry 45 (1984): 39-46

7. Pary RJ, Klontz W, Foxworth JM "Cholinergic rebounds and withdrawal syndromes ." Am J Psychiatry 137 (1980): 261

8. Galynker II, Rosenthal RN, Perkel C, Shwartz A "Doxepin withdrawal mania." J Clin Psychiatry 56 (1995): 122-3

9. Santos AB, Jr Mccurdy L "Delirium after abrupt withdrawal from doxepin: case report." Am J Psychiatry 137 (1980): 239-40

10. "Product Information. Sinequan (doxepin)." Roerig Division, New York, NY.

11. Dalton SO, Johansen C, Mellemkjaer L, Norgard B, Sorensen HT, Olsen JH "Use of selective serotonin reuptake inhibitors and risk of upper gastrointestinal tract bleeding: a population-based cohort study." Arch Intern Med 163 (2003): 59-64

12. Linnoila M, Jobson KO, Gilliam JH, Paine RL "Effects of doxepin on blood pressure and heart rate in patients with primary major affective disorder ." J Clin Psychopharmacol 2 (1982): 433-4

13. Strasberg B, Coelho A, Welch W, Swiryn S, Bauernfeind R, Rosen K "Doxepin induced torsade de pointes." Pacing Clin Electrophysiol 5 (1982): 873-7

14. Alter P, Tontsch D, Grimm W "Doxepin-induced torsade de pointes tachycardia." Ann Intern Med 135 (2001): 384-5

15. Baker B, Dorian P, Sandor P, Shapiro C, Schell C, Mitchell J, Irvine MJ "Electrocardiographic effects of fluoxetine and doxepin in patients with major depressive disorder." J Clin Psychopharmacol 17 (1997): 1521

16. Burrows GD, Vohra J, Hunt D, Sloman JG, Scoggins BA, Davies B "Cardiac effects of different tricyclic antidepressant drugs." Br J Psychiatry 129 (1976): 335-41

17. Roose SP, Dalack GW, Glassman AH, Woodring S, Walsh BT, Giardina EG "Is doxepin a safer tricyclic for the heart?" J Clin Psychiatry 52 (1991): 338-41

18. Luchins DJ "Review of clinical and animal studies comparing the cardiovascular effects of doxepin and other tricyclic antidepressants." Am J Psychiatry 140 (1983): 1006-9

19. Abbott R "Hyponatremia due to antidepressant medications." Ann Emerg Med 12 (1983): 708-10

20. Spigset O, hedenmalm K "Hyponatremia in relation to treatment with antidepressants: a survey of reports in the World Health Organization data base for spontaneous reporting of adverse drug reactions." Pharmacotherapy 17 (1997): 348-52

21. Smedley HM "Malignant breast change in man given two drugs associated with breast hyperplasia ." Lancet 2 (1981): 638-9

22. Wolf B, Conradty M, Grohmann R, Ruther E, Witzgall H, Londong V "A case of immune complex hemolytic anemia, thrombocytopenia, and acute renal failure associated with doxepin use." J Clin Psychiatry 50 (1989): 99-100

23. Keegan AD "Doxepin-induced recurrent acute hepatitis." Aust N Z J Med 23 (1993): 523

24. Podevin P, Biour M "Drug-induced ''allergic hepatitis''." Clin Rev Allergy Immunol 13 (1995): 223-44

It is possible that some side effects of Sinequan may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.