Venlafaxine ER

generic for Effexor XR

Venlafaxine ER Side Effects

See also Warning section.

Nausea, drowsiness, dizziness, dry mouth, constipation, loss of appetite, blurred vision, nervousness, trouble sleeping, unusual sweating, or yawning may occur. If any of these effects persist or worsen, tell your doctor promptly.

Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

This medication may raise your blood pressure. Check your blood pressure regularly and tell your doctor if the results are high.

Tell your doctor right away if any of these unlikely but serious side effects occur: easy bruising/bleeding, decreased interest in sex, changes in sexual ability, muscle cramps/weakness, shaking (tremor).

Get medical help right away if any of these rare but serious side effects occur: cough that doesn't go away, shortness of breath, chest pain, severe/pounding headache, black/bloody stools, vomit that looks like coffee grounds, eye pain/swelling/redness, widened pupils, vision changes (such as seeing rainbows around lights at night), seizure.

This medication may increase serotonin and rarely cause a very serious condition called serotonin syndrome/toxicity. The risk increases if you are also taking other drugs that increase serotonin, so tell your doctor or pharmacist of all the drugs you take (see Drug Interactions section). Get medical help right away if you develop some of the following symptoms: fast heartbeat, hallucinations, loss of coordination, severe dizziness, severe nausea/vomiting/diarrhea, twitching muscles, unexplained fever, unusual agitation/restlessness.

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US -

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.
  • hypoglycemic disorder
  • hyperprolactinemia
  • SIADH syndrome
  • hypercholesterolemia
  • hyponatremia
  • aplastic anemia
  • thrombocytopenic disorder
  • agranulocytosis
  • neutropenic disorder
  • acute confusion
  • manic disorder
  • hypomania
  • mood changes
  • depersonalization
  • suicidal ideation
  • abnormal sexual function
  • libido changes
  • disorder of ejaculation
  • bruxism
  • agitation
  • hostility
  • tardive dyskinesia
  • extrapyramidal disease
  • neuroleptic malignant syndrome
  • serotonin syndrome
  • migraine
  • ocular hypertension
  • accommodation disorder
  • blurred vision
  • visual changes
  • mydriasis
  • tinnitus
  • hyperacusis
  • hypertension
  • abnormal ECG
  • torsades de pointes
  • ventricular fibrillation
  • prolonged QT interval
  • orthostatic hypotension
  • hemorrhage
  • ecchymosis
  • vasodilation of blood vessels
  • rhinitis
  • sinusitis
  • bronchitis
  • interstitial pneumonitis
  • eosinophilic pneumonia
  • xerostomia
  • dyspepsia
  • constipation
  • hepatitis
  • gastrointestinal hemorrhage
  • erectile dysfunction
  • vaginitis
  • dysmenorrhea
  • menorrhagia
  • abnormal vaginal bleeding
  • skin photosensitivity
  • erythema multiforme
  • toxic epidermal necrolysis
  • Stevens-Johnson syndrome
  • pruritus of skin
  • alopecia
  • urticaria
  • neck pain
  • hypertonia
  • rhabdomyolysis
  • muscle rigidity
  • drowsy
  • delirium
  • altered mental status
  • seizure disorder
  • vertigo
  • dizziness
  • insomnia
  • flu-like symptoms
  • hyperhidrosis
  • chills
  • tremor
  • trismus
  • muscle fasciculation
  • akathisia
  • dysgeusia
  • ataxia
  • skin rash
  • edema
  • peripheral edema
  • flushing
  • anorexia
  • weight gain
  • weight loss
  • headache disorder
  • epistaxis
  • palpitations
  • dyspnea
  • yawning
  • chest pain
  • nausea
  • vomiting
  • flatulence

Drug Interactions

Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

Some products that may interact with this drug include: other drugs that can cause bleeding/bruising (including antiplatelet drugs such as clopidogrel, NSAIDs such as ibuprofen/naproxen, "blood thinners" such as dabigatran/warfarin).

Aspirin can increase the risk of bleeding when used with this medication. However, if your doctor has directed you to take low-dose aspirin for heart attack or stroke prevention (usually at dosages of 81-325 milligrams a day), you should continue taking it unless your doctor instructs you otherwise. Ask your doctor or pharmacist for more details.

Taking MAO inhibitors with this medication may cause a serious (possibly fatal) drug interaction. Avoid taking MAO inhibitors (isocarboxazid, linezolid, methylene blue, moclobemide, phenelzine, procarbazine, rasagiline, safinamide, selegiline, tranylcypromine) during treatment with this medication. Most MAO inhibitors should also not be taken for two weeks before and at least 7 days after treatment with this medication. Ask your doctor when to start or stop taking this medication.

The risk of serotonin syndrome/toxicity increases if you are also taking other drugs that increase serotonin. Examples include street drugs such as MDMA/"ecstasy," St. John's wort, certain antidepressants (including SSRIs such as fluoxetine/paroxetine, other SNRIs such as duloxetine/milnacipran), tryptophan, among others. The risk of serotonin syndrome/toxicity may be more likely when you start or increase the dose of these drugs.

Tell your doctor or pharmacist if you are taking other products that cause drowsiness such as opioid pain or cough relievers (such as codeine, hydrocodone), alcohol, marijuana (cannabis), drugs for sleep or anxiety (such as alprazolam, lorazepam, zolpidem), muscle relaxants (such as carisoprodol, cyclobenzaprine), or antihistamines (such as cetirizine, diphenhydramine).

Check the labels on all your medicines (such as allergy or cough-and-cold products) because they may contain ingredients that cause drowsiness. Ask your pharmacist about using those products safely.

Venlafaxine is very similar to desvenlafaxine. Do not take medications containing desvenlafaxine while using venlafaxine.

This medication may interfere with certain lab tests (including urine tests for amphetamines), possibly causing false test results. Make sure lab personnel and all your doctors know you use this drug.