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Sinequan Side Effects

Generic Name: doxepin

Note: This document contains side effect information about doxepin. Some of the dosage forms listed on this page may not apply to the brand name Sinequan.

For the Consumer

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

Along with its needed effects, doxepin (the active ingredient contained in Sinequan) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking doxepin:

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

Get emergency help immediately if any of the following symptoms of overdose occur while taking doxepin:

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

Some side effects of doxepin may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions 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


Capsules and Oral Concentrate: The most frequently reported side effects were constipation, dry mouth, and drowsiness.

Tablets (3 and 6 mg): The most frequently reported side effects were somnolence/sedation, nausea, and upper respiratory tract infection.[Ref]

Nervous system

Common (1% to 10%): Somnolence/sedation
Frequency not reported: Drowsiness, numbness, paresthesia, ataxia, extrapyramidal symptoms, seizure, tardive dyskinesia, tremor, dizziness, headache, neuroleptic malignant-like syndrome, convulsion, hyperreflexia in neonate, lethargy, syncope, ageusia, cerebrovascular accident, disturbance in attention, migraine, sleep paralysis, syncope vasovagal
Postmarketing reports: Hypoesthesia, dysgeusia[Ref]


Common (1% to 10%): Hypertension
Frequency not reported: Hypotension, flushing, tachycardia, ECG changed, postural hypotension, atrioventricular block, palpitation, ventricular extrasystole, ECG ST-T segment abnormal, ECG QRS complex abnormal, heart rate decreased, QRS axis abnormal, pallor, blood pressure inadequately controlled, hematoma, hot flush
Postmarketing reports: Arrhythmia, conduction disorder[Ref]


Common (1% to 10%): Gastroenteritis, nausea
Frequency not reported: Dry mouth, constipation, vomiting, indigestion, taste disturbance, diarrhea, anorexia, aphthous stomatitis, abdominal pain, gastroesophageal reflux disease, dyspepsia, gingival recession, hematochezia, lip blister
Postmarketing reports: Tongue edema, upper abdominal pain[Ref]


Common (1% to 10%): Upper respiratory tract infection/nasopharyngitis
Frequency not reported: Asthma exacerbated, respiratory depression in neonate, bronchitis, laryngitis, sinusitis, lower respiratory tract infection, pharyngitis, pneumonia, nasal congestion, pharyngolaryngeal pain, sinus congestion, wheezing, cough, crackles lung, nasopharyngeal disorder, rhinorrhea, dyspnea[Ref]


Frequency not reported: Confusion, disorientation, hallucination, libido decreased, libido increased, withdrawal symptom, agitation, anxiety, nervousness, aggressive reaction, suicidal ideation, suicidal behavior, insomnia, nightmare, mania exacerbated, paranoid delusions exacerbated, dream abnormal, adjustment disorder, depression, elevated mood[Ref]


Frequency not reported: Edema, tinnitus, weight gain, chills, fatigue, weakness, hyperpyrexia, asthenia, bone fracture, drug tolerance, ear pain, hypoacusis, motion sickness, tympanic membrane perforated, chest pain, gait abnormal, peripheral edema, fungal infection, tooth infection, viral infection, cellulitis staphylococcal, folliculitis, gastroenteritis viral, herpes zoster, infective tenosynovitis, influenza, onychomycosis, back injury, fall, joint sprain, skin laceration, sensation of heaviness, arthrodesis
Postmarketing reports: Malaise[Ref]


Frequency not reported: Gynecomastia, breasts enlarged, galactorrhea, testicular swelling, syndrome of inappropriate antidiuretic hormone[Ref]


Frequency not reported: Lung adenocarcinoma stage I, malignant melanoma, breast cyst[Ref]


Frequency not reported: Urinary retention, urinary tract infection, dysmenorrhea, dysuria, enuresis, hemoglobinuria, nocturia[Ref]


Frequency not reported: Eosinophilia, bone marrow depression, agranulocytosis, leukopenia, thrombocytopenia, hemolytic anemia, thrombocythemia, anemia, neutrophil count decreased[Ref]


Frequency not reported: Jaundice, hepatitis, hepatic abnormality, hyperbilirubinemia, ALT increased, transaminases increased[Ref]


Frequency not reported: Arthralgia, back pain, myalgia, neck pain, pain in extremity, muscle cramp, joint range of motion decreased[Ref]


Frequency not reported: Rash, pruritus, photosensitivity, purpura, sweating, alopecia, face edema, urticaria, hyperhidrosis, cold sweat, skin irritation, dermatitis, erythema, rosacea[Ref]


Frequency not reported: Hypersensitivity[Ref]


Frequency not reported: Blood sugar increased, blood sugar decreased, appetite increased, anorexia, appetite decreased, hyperkalemia, hypermagnesemia, hypokalemia[Ref]


Frequency not reported: Vision blurred, angle closure glaucoma, mydriasis, intraocular pressure increased, eye redness, blepharospasm, diplopia, eye pain, lacrimation decreased, eye infection[Ref]


1. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

2. Cerner Multum, Inc. "Australian Product Information." O 0

3. "Product Information. Silenor (doxepin)." Somaxon Pharmaceuticals, San Diego, CA.

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

Some side effects of Sinequan may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

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.