Venlafaxine Side Effects

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

For the Consumer

Applies to venlafaxine: oral capsule extended release, oral tablet, oral tablet extended release

As well as its needed effects, venlafaxine may cause unwanted side effects that require medical attention.

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

More common
  • High blood pressure
  • lack or loss of strength
  • severe headache
  • sweating
Less common
  • Blurred vision
  • chest pain
  • fast or irregular heartbeat
  • mood or mental changes
  • ringing or buzzing in the ears
  • suicidal thoughts
Rare
  • Actions that are out of control
  • convulsions
  • high fever
  • high or low blood pressure
  • irritability
  • itching or skin rash
  • lightheadedness or fainting, especially when getting up suddenly from a sitting or lying position
  • menstrual changes
  • nervousness
  • problems with urinating or holding urine
  • severe muscle stiffness
  • talking, feeling, and acting with excitement that you cannot control
  • trouble breathing
  • unusually pale skin
Incidence not known
  • Agitation
  • bloody, black, or tarry stools
  • bloody stool or urine
  • confusion
  • dark urine
  • decreased frequency or amount of urine
  • diarrhea
  • drowsiness
  • fever
  • general feeling of tiredness or weakness
  • headache
  • increased thirst
  • light-colored stools
  • muscle cramps, spasms, or pain
  • nausea or vomiting
  • nosebleeds
  • overactive reflexes
  • poor coordination
  • red or purple spots on skin
  • restlessness
  • shivering
  • stomach pain on upper right side
  • swelling of the face, lower legs, ankles, hands, or fingers
  • trembling or shaking that is hard to control
  • twitching
  • unusual bruising
  • unusual tiredness or weakness
  • vomiting of blood or material that looks like coffee grounds
  • yellow eyes or skin

Some venlafaxine 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:

More common
  • Abnormal dreams
  • chills
  • constipation
  • decrease in sexual desire or ability
  • diarrhea
  • drowsiness
  • dry mouth
  • heartburn
  • increased sweating
  • loss of appetite
  • nausea
  • stomach pain or gas
  • stuffy or runny nose
  • tingling, burning, or prickly sensations
  • trembling or shaking
  • trouble sleeping
  • unusual tiredness or weakness
  • vomiting
  • weight loss
Less common
  • Change in taste
  • muscle tension
  • yawning
Incidence not known
  • Night sweats

For Healthcare Professionals

Applies to venlafaxine: oral capsule extended release, oral tablet, oral tablet extended release

Gastrointestinal

Gastrointestinal side effects have frequently included nausea (up to 35%), dry mouth (14% to 18%), constipation (12%), anorexia (12% to 23%), vomiting, diarrhea (5% to 12%), eructation, abdominal pain, and flatulence.

Gastrointestinal side effects reported in premarketing Phase 3 trials have included increased appetite, bruxism, colitis, dysphagia, tongue edema, esophagitis, gastritis, gastroenteritis, gastrointestinal ulcer, gingivitis, glossitis, rectal hemorrhage, hemorrhoids, melena, oral moniliasis, stomatitis, mouth ulceration, abdominal distention, biliary pain, cheilitis, cholecystitis, cholelithiasis, esophageal spasms, duodenitis, hematemesis, gastroesophageal reflux disease, gastrointestinal hemorrhage, gum hemorrhage, hepatitis, ileitis, jaundice, intestinal obstruction, liver tenderness, parotitis, periodontitis, proctitis, rectal disorder, salivary gland enlargement, increased salivation, soft stools, and tongue discoloration.

Nervous system

Nervous system side effects have frequently included dizziness (16%), somnolence (up to 14%), insomnia (11% to 25%), fatigue (11%), nervousness (9%), abnormal dreams, sleep abnormalities, tremor, depression, paresthesia, decreased libido, agitation, hypertonia, anxiety, delirium, and twitching. The reported incidence of each of these effects ranges between 10% and 20% of treated patients. Dyskinesia has also been reported.

Venlafaxine has been reported to increase the pain tolerance threshold to electrical sural nerve stimulation and the threshold at which pain increases (pain summation).

One case of serotonin syndrome has been reported which is believed to have been precipitated by the combination of venlafaxine and trazodone.

One small study has suggested that venlafaxine may improve attention, concentration, memory, and reaction time performance after single oral doses.

Nervous system side effects reported in premarketing Phase 3 trials have included amnesia, confusion, depersonalization, hypesthesia, abnormal thinking, trismus, vertigo, akathisia, apathy, ataxia, circumoral paresthesia, central nervous system (CNS) stimulation, hostility, hyperesthesia, hyperkinesia, hypotonia, incoordination, myoclonus, neuralgia, neuropathy, seizure, abnormal speech, stupor, adjustment disorder, akinesia, alcohol abuse, aphasia, bradykinesia, buccoglossal syndrome, cerebrovascular accident, feeling drunk, loss of consciousness, dementia, dystonia, increased energy, facial paralysis, abnormal gait, Guillain-Barre Syndrome, hyperchlorhydria, hypokinesia, hysteria, impulse control difficulties, increased libido, motion sickness, neuritis, nystagmus, paresis, decreased or increased reflexes, and torticollis. Although these events occurred during treatment with venlafaxine, causality has not been determined.

Impaired coordination and balance have been reported in postmarketing studies.

Seizures have been reported in 0.26% of treated patients during premarketing testing. The manufacturer recommends that therapy be discontinued in patients who develop seizures.

The impact of venlafaxine on pain summation may indicate a potential analgesic effect for clinical neuropathic pain.

Nearly all selective serotonin reuptake inhibitors, mixed serotonin/norepinephrine reuptake inhibitors, and tricyclic antidepressants cause sleep abnormalities to some extent. These antidepressants have marked dose-dependent effects on rapid eye movement (REM) sleep, causing reductions in the overall amount of REM sleep over the night and delays the first entry into REM sleep (increased REM sleep onset latency (ROL)), both in healthy subjects and depressed patients. The antidepressants that increase serotonin function appear to have the greatest effect on REM sleep. The reduction in REM sleep is greatest early in treatment, but gradually returns towards baseline during long-term therapy; however, ROL remains long. Following discontinuation of therapy the amount of REM sleep tends to rebound. Some of these drugs (i.e., bupropion, mirtazapine, nefazodone, trazodone, trimipramine) appear to have a modest or minimal effect on REM sleep.

Cardiovascular

Cardiovascular side effects have frequently included vasodilatation, hypertension, palpitation, postural hypotension, and tachycardia.

Cardiovascular side effects reported in premarketing Phase 3 trials have included angina pectoris, arrhythmia, bradycardia, extrasystoles, hypotension, peripheral vascular disorder (mainly cold feet and/or cold hands), syncope, thrombophlebitis, aortic aneurysm, arteritis, first-degree atrioventricular block, bigeminy, bundle branch block, capillary fragility, cerebral ischemia, coronary artery disease, congestive heart failure, heart arrest, hematoma, cardiovascular disorder (mitral valve and circulatory disturbance), mucocutaneous hemorrhage, myocardial infarct, pallor, and sinus arrhythmia. Although these events occurred during treatment with venlafaxine, causality has not been determined.

There have been postmarketing reports of angioedema.

There are reports of sustained hypertension (some requiring immediate treatment). Experience with the immediate-release venlafaxine showed that sustained hypertension was dose-related, increasing from 3% to 7% at 100 to 300 mg/day to 13% at doses above 300 mg/day. There are not sufficient data with the use of venlafaxine extended-release at doses above 300 mg/day to determine the incidence of sustained increases in blood pressure at these high doses.

One study has reported average systolic blood pressure increases of 1.7 to 3.4 mm Hg and average diastolic pressure increases of 0.4 to 2.6 mm Hg. The same study reported an increase in the average pulse rate of 1.1 to 4.5 beats per minute.

Another study (n=7) suggests that venlafaxine may promote adverse cardiovascular and cerebrovascular events by increasing platelet activity in susceptible patients.

An increase in heart rate of 4 beats per minute has been reported.

According to a retrospective review, in the overdose setting (up to 3 g of venlafaxine), tachycardia, hypertension, mydriasis, QTc prolongation, and transient arrhythmia can be expected. Tachycardia and QTc prolongation appear to occur in a dose-dependent manner.

In one case report, venlafaxine (75 mg 3 times/day) may have contributed to an elevation in defibrillation threshold in a patient with nonischemic cardiomyopathy and an implantable cardioverter- defibrillator. Additional data are required to confirm this finding.

Genitourinary

Genitourinary side effects have frequently included male and female sexual dysfunction such as abnormal ejaculation in up to 16% of male patients, decreased libido (13%), impotence (13%), and organic dysfunction (anorgasmia or abnormal orgasm) in up to 8% of female patients.

Genitourinary side effects reported in premarketing Phase 3 trials have included prostatic disorder (prostatitis, enlarged prostate, and prostate irritability), impaired urination, albuminuria, amenorrhea, cystitis, dysuria, hematuria, leukorrhea, menorrhagia, metrorrhagia, nocturia, breast pain, polyuria, urinary incontinence, urinary retention, urinary urgency, vaginal hemorrhage, vaginitis, abortion, anuria, breast discharge, breast engorgement, balanitis, breast enlargement, endometriosis, female lactation, fibrocystic breast, calcium crystalluria, cervicitis, orchitis, ovarian cyst, bladder pain, prolonged erection, gynecomastia (male), hypomenorrhea, mastitis, menopause, oliguria, salpingitis, urolithiasis, uterine hemorrhage, uterine spasm, and vaginal dryness. Although these events occurred during treatment with venlafaxine, causality has not been determined.

There is a single case report of breast pain associated with venlafaxine therapy.

One case of unexpected orgasm and subsequent ejaculation with no erection as well as orgasmic episodes with no ejaculation or erection has also been reported. A case of increased libido and spontaneous erections has also been reported.

Although rare, several cases of venlafaxine- induced urinary symptoms including nocturia, enuresis, increased urge/frequency, and incontinence have been reported. Symptoms resolved following discontinuation of therapy.

Dermatologic

Dermatologic side effects have included sweating in up to approximately 14% of treated patients. Dermatologic side effects reported in premarketing Phase 3 trials have included pruritus, acne, alopecia, contact dermatitis, dry skin, eczema, maculopapular rash, psoriasis, urticaria, brittle nails, erythema nodosum, exfoliative dermatitis, lichenoid dermatitis, hair discoloration, skin discoloration, furunculosis, hirsutism, leukoderma, miliaria, petechial rash, pruritic rash, pustular rash, vesiculobullous rash, seborrhea, skin atrophy, skin hypertrophy, skin striae, and decreased sweating. Although these events occurred during treatment with venlafaxine, causality has not been determined. There have been postmarketing reports of toxic epidermal necrolysis and angioedema.

One case of venlafaxine induced Stevens-Johnson syndrome has been reported. Symptoms resolved following treatment with IV steroids and antidepressant therapy was safely switched to paroxetine. In addition, at least one case of photo induced telangiectasia has been associated with venlafaxine use.

At least 3 cases of venlafaxine- induced alopecia have been reported. In all cases, hair re- growth occurred within 2 to 4 weeks following discontinuation of venlafaxine.

Other

Withdrawal effects occur upon abrupt discontinuation of treatment and the severity of symptoms appears to be dependent on length of therapy and dose (including low dose therapy). Symptoms can be minimized by slow tapering or switching to a drug with a longer half-life (e.g., fluoxetine). Withdrawal symptoms were reported to include brief bursts of dizziness associated with headache, anxiety, irritability, agitation, insomnia, paresthesias, nausea, vomiting, diarrhea, tremor, fatigue, sweating, and worsening of depression (similar to symptoms reported after withdrawal from selective serotonin reuptake inhibitors). The onset of withdrawal symptoms ranges from 14 to 48 hours after the last dose of venlafaxine extended-release and symptoms tend to resolve rapidly (range, within 2 to 24 hours) after resumption of therapy. In the event that therapy is not reintroduced, withdrawal symptoms may last from 5 to 7 days before resolving spontaneously.

In one case report, withdrawal- induced full mania developed in a 33- year- old patient following abrupt termination of treatment with venlafaxine extended-release (150 mg daily for 10 weeks).

Other side effects have frequently included asthenia (up to 21%), headache (up to 34%), flu syndrome (6%), and accidental injury (5%).

Other side effects reported in premarketing Phase 3 trials have included edema, hyperacusis, otitis media, parosmia, loss of taste, deafness, labyrinthitis, otitis externa, substernal chest pain, chills, fever, neck pain, face edema, intentional injury, malaise, moniliasis, neck rigidity, pelvic pain, photosensitivity reaction, suicide attempt, appendicitis, bacteremia, carcinoma, and cellulitis. Although these events occurred during treatment with venlafaxine, causality has not been determined.

One case of anasarca was reported in a patient receiving venlafaxine. Following discontinuation of venlafaxine, symptoms resolved within approximately 72 hours. The authors state that it is possible that the anasarca was due to an allergic or delayed- type hypersensitivity reaction given the circumstances.

There are numerous case reports of withdrawal symptoms following abrupt discontinuation of treatment, and a single case report of severe tinnitus associated with venlafaxine.

Hepatic

Hepatic side effects have included toxic hepatitis. In one case, toxic hepatitis associated with low dose (37.5 mg/day) venlafaxine was reported in a patient with a history of chronic hepatitis.

Endocrine

Endocrine side effects have included flushing.

Endocrine side effects reported in premarketing Phase 3 trials have rarely included galactorrhea, goiter, hyperthyroidism, hypothyroidism, thyroid nodule, and thyroiditis. Although these events occurred during treatment with venlafaxine, causality has not been determined.

Psychiatric

Psychiatric side effects have included visual hallucinations, hypomania, and mania.

Psychiatric side effects reported in premarketing Phase 3 trials have included emotional lability, delusions, euphoria, hallucinations, manic reaction, psychosis, suicidal ideation, abnormal/changed behavior, homicidal ideation, paranoid reaction, and psychotic depression. Although these events occurred during treatment with venlafaxine, causality has not been determined.

Hematologic

Hematologic side effects have included have frequently included abnormal bleeding (most commonly ecchymosis).

Hematologic side effects reported in premarketing Phase 3 trials have included anemia, leukocytosis, leukopenia, lymphadenopathy, thrombocythemia, basophilia, increased bleeding time, cyanosis, eosinophilia, lymphocytosis, multiple myeloma, purpura, and thrombocytopenia. Although these events occurred during treatment with venlafaxine, causality has not been determined.

Musculoskeletal

Musculoskeletal side effects have included rhabdomyolysis.

Musculoskeletal side effects reported in premarketing Phase 3 trials have included arthralgia, arthritis, arthrosis, bone spurs, bursitis, leg cramps, myasthenia, tenosynovitis, bone pain, pathological fracture, muscle cramp, muscle spasms, musculoskeletal stiffness, myopathy, osteoporosis, osteosclerosis, plantar fasciitis, rheumatoid arthritis, and tendon rupture. Although these events occurred during treatment with venlafaxine, causality has not been determined.

Ocular

Ocular side effects have included abnormal vision, primarily blurred vision, in approximately 6% of patients. Angle-closure glaucoma has been reported rarely.

Ocular side effects reported in premarketing Phase 3 trials have included abnormality of accommodation, mydriasis, conjunctivitis, diplopia, dry eyes, eye pain, photophobia, visual field defect, blepharitis, cataract, chromatopsia, conjunctival edema, corneal lesion, exophthalmos, eye hemorrhage, glaucoma, retinal hemorrhage, subconjunctival hemorrhage, keratitis, miosis, papilledema, decreased pupillary reflex, scleritis, and uveitis. Although these events occurred during treatment with venlafaxine, causality has not been determined.

A case of dose-related increase of intraocular pressure caused by venlafaxine use has been reported.

Metabolic

A recent short-term study (6 weeks) has reported an average weight loss of 2 to 3 pounds in patients treated with venlafaxine.

Numerous cases of hyponatremia have been reported following treatment with a selective serotonin reuptake inhibitor (SSRI). Risk factors for the development of SSRI- associated hyponatremia including advanced age, female gender, concomitant use of diuretics, low body weight, and lower baseline serum sodium levels have been identified. Hyponatremia tends to develop within the first few weeks of treatment (range 3 to 120 days) and typically resolves within 2 weeks (range 48 hours to 6 weeks) after therapy has been discontinued with some patients requiring treatment. The proposed mechanism for the development of hyponatremia involves the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) via release of antidiuretic hormone.

Use of venlafaxine has been associated with small but statistically significant increases in total cholesterol, high- density lipoprotein cholesterol and low- density lipoprotein cholesterol.

Metabolic side effects have included weight loss (3%).

Metabolic side effects reported in premarketing Phase 3 trials have included weight gain, increased alkaline phosphatase, dehydration, hypercholesteremia, hyperglycemia, hyperlipemia, hypoglycemia, hypokalemia, increased SGOT (AST), increased SGPT (ALT), thirst, bilirubinemia, increased BUN, increased creatinine, diabetes mellitus, glycosuria, gout, abnormal healing, hemochromatosis, hypercalcinuria, hyperkalemia, hyperphosphatemia, hyperuricemia, hypocholesteremia, hyponatremia, hypophosphatemia, hypoproteinemia, and uremia. Although these events occurred during treatment with venlafaxine, causality has not been determined.

There have been a minimum of approximately fifteen cases of hyponatremia in which at least one was life threatening, including at least one case of recurrent venlafaxine- induced hyponatremia after rechallenge.

Renal

Renal side effects reported in premarketing Phase 3 trials have included kidney calculus, kidney pain, abnormal kidney function, and pyelonephritis. Although these events occurred during treatment with venlafaxine, causality has not been determined.

Respiratory

Respiratory side effects have frequently included pharyngitis, sinusitis, and yawning.

Respiratory side effects reported in premarketing Phase 3 trials have included increased cough, dyspnea, asthma, chest congestion, epistaxis, hyperventilation, laryngismus, laryngitis, pneumonia, voice alteration, atelectasis, hemoptysis, hypoventilation, hypoxia, larynx edema, pleurisy, pulmonary embolus, and sleep apnea. Although these events occurred during treatment with venlafaxine, causality has not been determined.

Although rare, interstitial pneumonitis secondary to venlafaxine therapy has been reported. The onset of venlafaxine- associated interstitial pneumonitis has ranged from 1 to 18 months after initial exposure to the drug and symptomatic improvement occurred after discontinuation of venlafaxine and treatment with corticosteroids.

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