Effexor Side Effects

Generic name: venlafaxine

Medically reviewed by Drugs.com. Last updated on Sep 23, 2024.

Note: This document provides detailed information about Effexor Side Effects associated with venlafaxine. Some dosage forms listed on this page may not apply specifically to the brand name Effexor.

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

Precautions

If you will be taking this medicine for a long time, it is very important that your doctor check you at regular visits. This will allow your doctor to see if the medicine is working properly and to decide if you should continue to take it.

Do not take venlafaxine (the active ingredient contained in Effexor) with a monoamine oxidase (MAO) inhibitor (eg, isocarboxazid (Marplan®), phenelzine (Nardil®)], selegiline (Eldepryl®), tranylcypromine (Parnate®)). Do not start taking venlafaxine during the 14 days after you stop a MAO inhibitor and wait 7 days after stopping venlafaxine before you start taking a MAO inhibitor. If you take them together or do not wait the proper amount of time, you may develop confusion, agitation, restlessness, stomach or intestinal symptoms, a sudden high body temperature, an extremely high blood pressure, or severe seizures.

Venlafaxine may cause a serious condition called serotonin syndrome if taken together with certain medicines. Do not use venlafaxine with buspirone (Buspar®), fentanyl (Abstral®, Duragesic®), linezolid (Zyvox®), lithium (Eskalith®, Lithobid®), methylene blue injection, tryptophan, St John's wort, amphetamines, or some pain or migraine medicines (eg, meperidine, methadone, rizatriptan, sumatriptan, tramadol, Demerol®, Frova®, Imitrex®, Maxalt®, Methadose®, Relpax®, Ultram®, Zomig®). Check with your doctor first before taking any other medicines with venlafaxine.

This medicine may cause some teenagers and young adults to be agitated, irritable, or display other abnormal behaviors. It may also cause some people to have suicidal thoughts and tendencies or to become more depressed. Some people may have trouble sleeping, get upset easily, have a big increase in energy, or start to act reckless. If you or your caregiver notice any of these unwanted effects, tell your doctor right away. Let the doctor know if you or anyone in your family has bipolar disorder (manic-depressive) or has tried to commit suicide.

Do not suddenly Stop taking venlafaxine without checking first with your doctor. Your doctor may want you to gradually reduce the amount you are taking before stopping it completely. This will decrease the chance of side effects, including agitation, anxiety, blurred vision, confusion, diarrhea, dizziness, fast or irregular heartbeat, headache, irritability, nausea or vomiting, numbness or tingling feeling, restlessness, seizures, sweating, thoughts of hurting yourself or others, trouble sleeping, unusual dreams, or unusual drowsiness, tiredness, or weakness.

This medicine may cause hyponatremia (low sodium in the blood). This is more common in elderly patients, those who take diuretic medicines, or those who have a low amount of fluid in the body due to severe diarrhea or vomiting. Check with your doctor right away if you have a headache, trouble concentrating, memory problems, confusion, weakness, or feel unsteady when standing.

Venlafaxine may increase your risk for bleeding problems. Make sure your doctor knows if you are also using other medicines that thin the blood, including NSAIDs (eg, aspirin, diclofenac, ibuprofen, naproxen, Advil®, Aleve®, Celebrex®, Voltaren®) or warfarin (Coumadin®, Jantoven®).

Tell your doctor right away if you are having chest pain or discomfort, dry cough, fever, general feeling of tiredness or weakness, skin rash, or trouble breathing with this medicine. These might be symptoms of a serious lung problem, including interstitial lung disease and eosinophilic pneumonia.

Venlafaxine may cause some people to become drowsy or have blurred vision. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are not alert or able to see clearly. It is best to avoid alcohol with venlafaxine.

Before you have any medical tests, tell the medical doctor in charge that you are taking this medicine. The results of some tests may be affected by this medicine.

Check with your doctor right away if you have decreased interest in sexual intercourse, delayed or inability to have and orgasm in women, inability to have or keep an erection in men, or loss in sexual ability, desire, drive, or performance. These could be symptoms of sexual dysfunction.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

Serious side effects of Effexor

Along with its needed effects, venlafaxine 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 venlafaxine:

Other side effects of Effexor

Some side effects of venlafaxine 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:

For healthcare professionals

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

General adverse events

The most commonly reported side effects were nausea, headache, somnolence, and dizziness.^[Ref]

Gastrointestinal

• Very common (10% or more): Nausea (up to 58%), dry mouth (up to 22%), constipation (up to 15%)
• Common (1% to 10%): Abdominal pain, diarrhea, dyspepsia, eructation, flatulence, vomiting
• Uncommon (0.1% to 1%): Circumoral paresthesia, colitis, dysphagia, esophagitis, gastritis, gastroenteritis, gastrointestinal hemorrhage, gastrointestinal ulcer, gingivitis, glossitis, hemorrhoids, melena, mouth ulceration, oral moniliasis, rectal hemorrhage, stomatitis, tongue edema
• Rare (less than 0.1%): Abdominal distention, buccoglossal syndrome, cheilitis, cholecystitis, cholelithiasis, duodenitis, esophageal spasm, gastroesophageal reflux disease, gum hemorrhage, hematemesis, hyperchlorhydria, ileitis, increased salivation, intestinal obstruction, pancreatitis, parotitis, periodontitis, proctitis, salivary gland enlargement, soft stools, tongue discoloration^[Ref]

Nervous system

• Very common (10% or more): Headache (up to 38%), somnolence (up to 26.1%), dizziness (up to 23.9%), tremor (up to 10.2%)
• Common (1% to 10%): Akathisia, amnesia, dysgeusia, hypertonia, hypesthesia, increased muscle tone, migraine, paresthesia, sedation, taste perversion, vertigo
• Uncommon (0.1% to 1%): Abnormal coordination, abnormal speech, ataxia, balance disorder, central nervous system (CNS) stimulation, dyskinesia, hyperesthesia, hyperkinesia, hypotonia, incoordination, myoclonus, neuralgia, neuropathy, parosmia, seizure, syncope, stupor, taste loss, visual field defect
• Rare (0.1% to 0.01%): Abnormal gait, akinesia, aphasia, bradykinesia, cerebral ischemia, cerebrovascular accident, convulsion, dementia, dystonia, facial paralysis, Guillain-Barre Syndrome, hypokinesia, loss of consciousness, neuritis, neuroleptic malignant syndrome (NMS), nystagmus, paresis, reflexes decreased, reflexes increased, serotonin syndrome, torticollis
• Very rare (less than 0.01%): Extrapyramidal reactions, tardive dyskinesia
• Frequency not reported: Impaired coordination, sensory disturbance
• Postmarketing reports: Coordination abnormal, impaired balance, involuntary movements, NMS-like reactions, shock-like electrical sensations^[Ref]

Psychiatric

• Very common (10% or more): Insomnia (up to 24%), nervousness (up to 21.3%), abnormal orgasm (up to 12.5%), anxiety (up to 11.2%)
• Common (1% to 10%): Abnormal dreams, abnormal thinking, agitation, anorgasmia, confusion, depersonalization, depression, libido decreased, orgasm disturbance, orgasmic dysfunction
• Uncommon (0.1% to 1%): Apathy, bruxism, derealization, emotional lability, euphoria, hallucination, hostility, hypomania, libido increased, mania, manic reaction, psychosis, suicidal ideation, suicide attempt, withdrawal syndrome
• Rare (less than 0.1%): Alcohol abuse, delirium, delusions, homicidal ideation, hysteria, impulse control difficulties, paranoid reaction, psychotic depression, psychomotor restlessness
• Frequency not reported: Aggression, delayed orgasm, increased dreaming, intense dreams, nightmares, other sleep disorders, self-harm, sleep disturbances, suicidal behaviors, vivid dreams, withdrawal symptoms
• Postmarketing reports: Catatonia, confusional state, panic, paranoia, psychotic disorder^[Ref]

Dermatologic

• Very common (10% or more): Sweating (up to 19.3%), night sweats (up to 11.4%)
• Common (1% to 10%): Ecchymosis, hyperhidrosis, pruritus, rash
• Uncommon (0.1% to 1%): Acne, alopecia, brittle nails, contact dermatitis, dry skin, eczema, face edema, maculopapular rash, photosensitivity reaction, psoriasis, skin hypertrophy, urticaria
• Rare (less than 0.1%): Cellulitis, erythema multiforme, erythema nodosum, exfoliative dermatitis, furunculosis, granuloma, hair discoloration, hirsutism, leukoderma, lichenoid dermatitis, miliaria, mucocutaneous hemorrhage, petechial rash, pruritic rash, purpura, pustular rash, seborrhea, skin atrophy, skin discoloration, skin striae, Stevens-Johnson syndrome, sweating decreased, toxic epidermal necrolysis, vesiculobullous rash^[Ref]

Metabolic

• Very common (10% or more): Anorexia (up to 20%)
• Common (1% to 10%): Blood cholesterol increased, decreased appetite, increased appetite, weight gain, weight loss
• Uncommon (0.1% to 1%): Dehydration, hyperglycemia, hyperlipemia, hyperlipidemia, hypokalemia, hyponatremia, increased alkaline phosphatase, thirst
• Rare (less than 0.1%): Alcohol intolerance, diabetes mellitus, gout, hemochromatosis, hypercholesteremia, hyperkalemia, hyperphosphatemia, hyperuricemia, hypocholesteremia, hypoglycemia, hypophosphatemia, hypoproteinemia
• Frequency not reported: Height changes, loss of appetite, weight changes
• Postmarketing reports: Lactate dehydrogenase (LDH) increased^[Ref]

Other

• Very common (10% or more): Asthenia (up to 19%)
• Common (1% to 10%): Accidental injury, chills, fatigue, fever, tinnitus, trauma
• Uncommon (0.1% to 1%): Hyperacusis, intentional injury, malaise, otitis media
• Rare (less than 0.1%): Abortion, deafness, energy increased, feeling drunk, healing abnormal, labyrinthitis, menopause, motion sickness, otitis externa
• Frequency not reported: Discontinuation syndrome, pain
• Postmarketing reports: Congenital anomalies^[Ref]

Genitourinary

• Very common (10% or more): Abnormal ejaculation (up to 16%)
• Common (1% to 10%): Albuminuria, enlarged prostate, erectile dysfunction, impotence, metrorrhagia, pollakiuria, prostatic disorder, prostatitis, urinary frequency, urinary hesitation, urinary retention, urination impaired, vaginitis
• Uncommon (0.1% to 1%): Amenorrhea, bladder pain, breast pain, cystitis, dysuria, hematuria, leukorrhea, menorrhagia, nocturia, pelvic pain, polyuria, prostate irritability, pyuria, urinary incontinence, urinary urgency, vaginal hemorrhage
• Rare (less than 0.1%): Balanitis, breast discharge, breast engorgement, breast enlargement, calcium crystalluria, cervicitis, endometriosis, galactorrhea, hypercalcinuria, hypomenorrhea, lactation (female), mastitis, menstrual disorders associated with increased bleeding or increased irregular bleeding, ovarian cyst, orchitis, prolonged erection, salpingitis, urolithiasis, uterine hemorrhage, uterine spasm, vaginal dryness
• Frequency not reported: Delayed ejaculation, dysmenorrhea
• Postmarketing reports: Proteinuria^[Ref]

Cardiovascular

• Common (1% to 10%): Chest pain, edema, hot flashes/hot flush, hypertension/increased blood pressure, palpitation, postural hypotension, substernal chest pain, tachycardia, vasodilation
• Uncommon (0.1% to 1%): Angina pectoris, arrhythmia, bradycardia, cold feet, cold hands, extrasystoles, hypotension, orthostatic hypotension, peripheral vascular disorder, thrombophlebitis
• Rare (less than 0.1%): Aortic aneurysm, arteritis, bigeminy, bundle branch block, capillary fragility, cardiovascular disorder (mitral valve and circulatory disturbance), coronary artery disease, congestive heart failure, cyanosis, ECG QT prolonged, first-degree atrioventricular block, heart arrest, hematoma, myocardial infarct, pallor, sinus arrhythmia, torsade de pointes, ventricular fibrillation, ventricular tachycardia
• Postmarketing reports: Atrial fibrillation, deep vein thrombophlebitis, ECG abnormalities, stress cardiomyopathy, supraventricular tachycardia, Takotsubo cardiomyopathy, ventricular extrasystole^[Ref]

Respiratory

• Common (1% to 10%): Bronchitis, cough increased, dyspnea, pharyngitis, sinusitis, yawn/yawning
• Uncommon (0.1% to 1%): Asthma, chest congestion, epistaxis, hyperventilation, laryngismus, laryngitis, pneumonia, voice alteration
• Rare (less than 0.1%): Atelectasis, hemoptysis, hypoventilation, hypoxia, interstitial lung disease, larynx edema, pleurisy, pulmonary embolus, pulmonary eosinophilia, sleep apnea
• Frequency not reported: Rhinitis, upper respiratory infection, upper respiratory tract infection^[Ref]

Ocular

• Common (1% to 10%): Abnormality of accommodation, abnormal vision, blurred vision, mydriasis
• Uncommon (0.1% to 1%): Cataract, conjunctivitis, corneal lesion, diplopia, dry eyes, eye pain, photophobia
• Rare (less than 0.1%): Angle-closure glaucoma, blepharitis, chromatopsia, conjunctival edema, decreased pupillary reflex, exophthalmos, eye hemorrhage, keratitis, miosis, papilledema, retinal hemorrhage, scleritis, subconjunctival hemorrhage, uveitis
• Frequency not reported: Difficulty focusing eyes^[Ref]

Musculoskeletal

• Common (1% to 10%): Neck pain, trismus, twitching
• Uncommon (0.1% to 1%): arthritis, arthrosis, bone pain, bone spurs, bursitis, leg cramps, myasthenia, neck rigidity, tenosynovitis
• Rare (less than 0.1%): Muscle cramp, muscle spasms, musculoskeletal stiffness, myopathy, osteoporosis, osteosclerosis, pathological fracture, plantar fasciitis, rhabdomyolysis, rheumatoid arthritis, tendon rupture
• Frequency not reported: Arthralgia, back pain, myalgia
• Postmarketing reports: Bone fracture, creatine phosphokinase (CPK) increased^[Ref]

Immunologic

• Common (1% to 10%): Flu syndrome, infection
• Uncommon (0.1% to 1%): Moniliasis
• Rare (less than 0.1%): Appendicitis, bacteremia^[Ref]

Hematologic

• Uncommon (0.1% to 1%): Anemia, leukocytosis, leukopenia, lymphadenopathy, mucous membrane bleeding, mucosal hemorrhage, thrombocythemia, thrombocytopenia
• Rare (less than 0.1%): Agranulocytosis, aplastic anemia, basophilia, blood dyscrasias, eosinophilia, lymphocytosis, neutropenia, pancytopenia, prolonged bleeding time
• Postmarketing reports: INR increased, prolonged partial thromboplastin time, prothrombin time increased^[Ref]

Hepatic

• Uncommon (0.1% to 1%): Abnormal liver function tests, ALT increased, AST increased
• Rare (less than 0.1%): Biliary pain, bilirubinemia, cholecystitis, cholelithiasis, hepatitis, jaundice, liver tenderness
• Postmarketing reports: Fatty liver, GGT elevation, hepatic reactions, liver damage, liver failure, liver necrosis^[Ref]

Renal

• Uncommon (0.1% to 1%): Kidney calculus, kidney pain
• Rare (less than 0.1%): Anuria, blood urea nitrogen (BUN) increased, creatinine increased, glycosuria, kidney function abnormal, oliguria, pyelonephritis, uremia
• Postmarketing reports: Renal failure^[Ref]

Hypersensitivity

• Uncommon (0.1% to 1%): Angioedema
• Rare (less than 0.1%): Anaphylactic reaction, anaphylaxis
• Frequency not reported: Hypersensitivity^[Ref]

Endocrine

• Rare (0.1% to 0.01%): Goiter, gynecomastia (male), hyperthyroidism, hypothyroidism, inappropriate antidiuretic hormone secretion (SIADH)/syndrome of inappropriate antidiuretic hormone secretion, thyroid nodule, thyroiditis
• Very rare (less than 0.01%): Blood prolactin increased^[Ref]

Oncologic

• Rare (less than 0.1%): Carcinoma, fibrocystic breast, multiple myeloma^[Ref]

See also:

Frequently asked questions

• How long do venlafaxine withdrawal symptoms last?
• SSRIs vs SNRIs - What's the difference between them?

Further information

Effexor side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Note: Medication side effects may be underreported. If you are experiencing side effects that are not listed, submit a report to the FDA by following this guide.

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