Venlafaxine belongs to the class of antidepressant and anxiolytic medications known as serotonin and norepinephrine reuptake inhibitors (SNRIs). It is used to treat depression. It works on the central nervous system (CNS) to elevate mood in people with depression.

Venlafaxine is also used to treat the symptoms of anxiety causing distress in generalized anxiety disorder (GAD), social anxiety disorder (social phobia), and panic disorder (panic attacks). SNRIs work by increasing the amount of two chemicals called serotonin and norepinephrine, which are available in certain parts of the brain.

Symptoms may begin to improve within 2 weeks of starting venlafaxine, but it may take several weeks before the full beneficial effects of this medication are felt.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

37.5 mg
Each extended release, hard gelatin capsule with peach-coloured opaque body and gray opaque cap, the body has "VXR 37.5" and the cap has a logo both printed in red, contains 37.5 mg of venlafaxine HCl. Nonmedicinal ingredients: microcrystalline cellulose, povidone, talc, colloidal silicon dioxide, magnesium stearate, ethyl cellulose, and copovidone; hard capsules: gelatin and titanium dioxide.

75 mg
Each extended release, hard gelatin capsule with peach-coloured opaque body and cap, the body has "VXR 75" and the cap has a logo both printed in red, contains 75 mg of venlafaxine HCl. Nonmedicinal ingredients: microcrystalline cellulose, povidone, talc, colloidal silicon dioxide, magnesium stearate, ethyl cellulose, and copovidone; hard capsules: gelatin and titanium dioxide.

150 mg
Each extended release, hard gelatin capsule with dark orange opaque body and cap, the body has "VXR 150" and the cap has a logo both printed in white, contains 150 mg of venlafaxine HCl. Nonmedicinal ingredients: microcrystalline cellulose, povidone, talc, colloidal silicon dioxide, magnesium stearate, ethyl cellulose, and copovidone; hard capsules: gelatin and titanium dioxide.

37.5 mg
Each extended release, hard gelatin capsule with peach-coloured opaque body and gray opaque cap, the body has "VXR 37.5" and the cap has a logo both printed in red, contains 37.5 mg of venlafaxine HCl. Nonmedicinal ingredients: microcrystalline cellulose, povidone, talc, colloidal silicon dioxide, magnesium stearate, ethyl cellulose, and copovidone; hard capsules: gelatin.

75 mg
Each extended release, hard gelatin capsule with peach-coloured opaque body and cap, the body has "VXR 75" and the cap has a logo both printed in red, contains 75 mg of venlafaxine HCl. Nonmedicinal ingredients: microcrystalline cellulose, povidone, talc, colloidal silicon dioxide, magnesium stearate, ethyl cellulose, and copovidone; hard capsules: gelatin.

150 mg
Each extended release, hard gelatin capsule with dark orange opaque body and cap, the body has "VXR 150" and the cap has a logo both printed in white, contains 150 mg of venlafaxine HCl. Nonmedicinal ingredients: microcrystalline cellulose, povidone, talc, colloidal silicon dioxide, magnesium stearate, ethyl cellulose, and copovidone; hard capsules: gelatin.

Do not take venlafaxine if you:

• are allergic to venlafaxine or any ingredients of the medication
• are currently taking an MAO inhibitor (e.g., phenelzine, tranylcypromine), have taken one in the last 14 days, or will start treatment with one in the next 14 days

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• abnormal dreams
• constipation
• diarrhea
• dizziness
• drowsiness
• dry mouth
• headache
• loss of appetite
• nausea
• nervousness
• sweating
• sexual difficulties
• trouble sleeping
• unusual tiredness or weakness
• vision changes
• vomiting
• weight loss

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• abdominal pain
• agitation
• difficulty urinating
• fast heartbeat
• hallucinations (hearing or seeing things that aren't there)
• increased blood pressure
• new or worsening mood or mental changes (e.g., agitation, anger, aggression, anxiety, violent or suicidal thoughts)
• restlessness or inability to sit still
• signs of bleeding (e.g., unusual nosebleeds, bruising, blood in urine, coughing blood, bleeding gums, cuts that don't stop bleeding)
• signs of liver damage (e.g., yellowing of the skin and eyes, abdominal pain, dark urine, clay-coloured stools, loss of appetite, or nausea and vomiting)
• skin prickling or rash
• symptoms of glaucoma (increased pressure in the eyes) (e.g., decreased or blurred vision, eye pain, red eye, swelling of the eye)

• symptoms of irregular heartbeat (e.g., chest pain, dizziness, rapid or pounding heartbeat, shortness of breath)

• signs of low sodium (e.g., tiredness, weakness, confusion, achy, stiff, uncoordinated muscles)
• symptoms of mania (e.g., irritability, elevated mood, decreased need for sleep, racing thoughts)
• tremor
• unusual or sudden body or facial movements or postures

Stop taking the medication and seek immediate medical attention if any of the following occur:

• attempts at suicide or thoughts of suicide or self-harm
• convulsions (seizures)
• serotonin syndrome (symptoms include confusion, diarrhea, fever, poor coordination, restlessness, shivering, sweating, trembling or shaking, or twitching)
• signs of an allergic reaction (e.g., difficulty breathing, hives, swelling of the face or throat)
• signs of bleeding in the stomach (e.g., bloody, black, or tarry stools; spitting up of blood; vomiting blood or material that looks like coffee grounds)
• signs of extremely high blood pressure (e.g., severe headache upon wakening that is concentrated in the back of the head and neck, fast or irregular heartbeat, dizziness, chest pain)
• symptoms of SIADH (e.g., darkened urine colour, nausea, vomiting, muscle cramps, confusion, seizures)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Allergic reactions: In rare cases, some people may develop an allergic reaction to this medication. Signs of an allergic reaction include a severe rash, swollen face, or difficulty breathing. If these occur, get immediate medical attention.

Behaviour changes or suicidal behaviour: Some people taking this medication experience erratic or aggressive behaviour, agitation, depressed mood, or they may have thoughts of harming themselves or others. If you experience any mood or behaviour changes, or if your friends or family observe any of these changes while you are taking this medication, stop taking this medication and contact your doctor immediately.

Bleeding disorders: Venlafaxine may increase bruising and bleeding from cuts may take longer to stop. If you have a bleeding disorder or a history of bleeding problems, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Blood pressure: Treatment with venlafaxine has been associated with increases in blood pressure. Your doctor may monitor your blood pressure while you are taking venlafaxine. Rarely, some people may experience a large increase in blood pressure. This extremely high blood pressure can cause rapid or irregular heartbeat, chest pain, dizziness, feeling overly tired, blurred vision, and symptoms of severe headache upon awakening that is mainly in the back of the head and neck region. If any of these symptoms occur, contact your doctor immediately.

Bone health and osteoporosis: Recent studies have shown that there may be an increased risk of bone fractures (breaks) with the use of venlafaxine and other antidepressants. People with osteoporosis or those with risk factors for developing osteoporosis, may be more likely to experience a fracture. If you have osteoporosis or are at risk for developing osteoporosis, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Cholesterol: Venlafaxine can cause higher blood cholesterol levels. If you are at risk of developing high cholesterol or you have high cholesterol levels before starting venlafaxine, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Drowsiness/reduced alertness: Venlafaxine may cause drowsiness or dizziness, affecting your ability to drive or operate machinery. Avoid these and other hazardous tasks until you have determined how this medication affects you.

Glaucoma: This medication may cause the symptoms of glaucoma (increased pressure in the eye) to become worse. If you have glaucoma, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. Report any changes in vision to your doctor as soon as possible while you are taking this medication.

Heart disease: If you have heart disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. Venlafaxine may cause increased blood pressure or increased cholesterol levels.

Kidney function:  Kidney disease or reduced kidney function may cause this medication to build up in the body, causing side effects. If you have kidney disease or reduced kidney function, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Liver function: Liver disease or reduced liver function may cause this medication to build up in the body, causing side effects. If you have liver problems, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. Your doctor may want to test your liver function regularly with blood tests while you are taking this medication.

If you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, contact your doctor immediately.

Mania/hypomania: Venlafaxine may cause activation of mania or hypomania. People with a history of bipolar disorder should be closely monitored by their doctor while taking this medication.

Neuroleptic malignant syndrome (NMS): Venlafaxine can rarely cause a potentially fatal syndrome known as neuroleptic malignant syndrome (NMS). If you notice the symptoms of NMS such as high fever, muscle stiffness, confusion or loss of consciousness, sweating, racing or irregular heartbeat, or fainting, get immediate medical attention.

Seizures: If you have a history of seizures, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Serotonin syndrome: This medication may cause a potentially life-threatening condition called serotonin syndrome, especially when used with other medications that increase serotonin levels (e.g., sumatriptan, rizatriptan). If you experience symptoms of serotonin syndrome such as agitation, hallucinations, fast heart rate, fever, lack of coordination, nausea, vomiting, and diarrhea, get immediate medical attention.

Sodium levels: Some people who take venlafaxine experience unusually low levels of sodium in the blood. This is more likely to be experienced by seniors, people taking diuretics (water pills), or those who are dehydrated. Decreased sodium levels in the blood may be caused by inappropriate antidiuretic hormone secretion (SIADH), a condition in which the body causes increased amounts of fluid to be retained by the kidneys. If you experience sudden nausea, vomiting, tremors, mood or personality changes, or seizures, contact your doctor as soon as possible.

Stopping the medication: Stopping this medication suddenly may lead to side effects. If you are thinking of stopping this medication, check with your doctor first. When stopping venlafaxine treatment after more than one week, it is recommended that the dose of the medication be reduced gradually to prevent symptoms such as anxiety, agitation, confusion, diarrhea, dizziness, dry mouth, fatigue, headache, nausea, loss of appetite, nervousness, sleep disturbances, sweating, and vomiting.

Pregnancy: Newborns whose birth parents take medications such as venlafaxine during the third trimester of pregnancy may experience complications that require prolonged hospitalization. These complications normally resolve over time. People who take venlafaxine in the last 3 months of pregnancy may also experience dangerously increased blood pressure or increased bleeding during delivery of the baby.

This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: This medication passes into breast milk. If you are breast-feeding and taking venlafaxine, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of this medication have not been established for children under 18 years old. There have been reports that using this and similar medications for children below the age of 18 may cause behavioural and emotional changes, such as suicidal thoughts and behaviour.

Seniors: Seniors may be more sensitive to the side effects of this medication.

There may be an interaction between venlafaxine and any of the following:

• abrocitinib
• acalabrutinib
• alcohol
• alpha-agonists (e.g., clonidine, methyldopa)
• alpha/beta-agonists (e.g., epinephrine, norepinephrine)
• amphetamines (e.g., dextroamphetamine, lisdexamfetamine)
• anagrelide
• anticoagulants (e.g., apixaban, edoxaban, dabigatran, rivaroxaban, warfarin)
• antiplatelet medications (e.g., acetylsalicylic acid [ASA], clopidogrel)
• antipsychotics (e.g., cariprazine, chlorpromazine, clozapine, haloperidol, olanzapine, quetiapine, risperidone)
• bismuth subsalicylate
• brimonidine
• bromocriptine
• buspirone
• butorphanol
• cabergoline
• cyclobenzaprine
• dasatinib
• desmopressin
• dextromethorphan
• domperidone
• ergot alkaloids (e.g., ergotamine, dihydroergotamine)
• guanfacine
• heparin
• herbal medications (e.g., garlic, ginger, ginkgo, ginseng)
• ibrutinib
• icosapent ethyl
• linezolid
• lithium
• low molecular weight heparins (e.g., dalteparin, enoxaparin, tinzaparin)
• methadone
• methylene blue
• methylphenidate
• metoclopramide
• mirtazapine
• monoamine oxidase inhibitors (MAOIs; e.g., moclobemide, phenelzine, rasagiline, selegiline, tranylcypromine)
• multivitamins with minerals
• narcotic pain relievers (e.g., codeine, fentanyl, morphine, oxycodone, tapentadol, tramadol)
• nonsteroidal anti-inflammatory drugs (NSAIDs; e.g., celecoxib, ibuprofen, indomethacin, naproxen)
• obinutuzumab
• omega-3 fatty acids
• ozanimod
• pentoxifylline
• pergolide
• prasugrel
• propafenone
• pseudoephedrine
• St. John's wort
• selective serotonin reuptake inhibitors (SSRIs; e.g., citalopram, fluoxetine, paroxetine, sertraline, vortioxetine)
• other serotonin / norepinephrine reuptake inhibitors (SNRIs; e.g., desvenlafaxine, duloxetine)
• serotonin antagonists (anti-emetic medications; e.g., granisetron, ondansetron)
• tacrolimus
• tipranavir
• tizanidine
• trazodone
• tricyclic antidepressants (e.g., amitriptyline, desipramine, imipramine)
• "triptan" migraine medications (e.g., sumatriptan, rizatriptan, zolmitriptan)
• tryptophan supplements
• vitamin E
• voriconazole
• zanubrutinib

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.