How does this medication work? What will it do for me?

Desvenlafaxine belongs to the class of antidepressant medications known as selective serotonin and norepinephrine reuptake inhibitors (SNRIs). It is used to treat depression.

It works on the central nervous system (CNS) to elevate mood by increasing the amount of 2 neurotransmitters (chemical messengers) called serotonin and norepinephrine that are available in certain parts of the brain. It may take several weeks before the full benefits of this medication are seen.

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.

What form(s) does this medication come in?

50 mg
Each light pink, square pyramid, extended-release tablet, debossed with "W" over "50" on the flat side, contains 50 mg of desvenlafaxine. Nonmedicinal ingredients: hypromellose, magnesium stearate, microcrystalline cellulose, talc; film coating: dextrose, maltodextrin, sodium carboxymethylcellulose, stearic acid, iron oxides, and titanium dioxide.

100 mg
Each reddish-orange, square pyramid, extended-release tablet, debossed with "W" over "100" on the flat side, contains 100 mg of desvenlafaxine. Nonmedicinal ingredients: hypromellose, magnesium stearate, microcrystalline cellulose, talc; film coating: dextrose, maltodextrin, sodium carboxymethylcellulose, stearic acid, iron oxides, and titanium dioxide.

How should I use this medication?

The recommended starting dose of desvenlafaxine for adults is 50 mg once daily at approximately the same time each day. If necessary, your doctor may increase your dose to a maximum of 100 mg daily.

Desvenlafaxine may be taken with or without food. This medication must be swallowed whole with fluid. Do not divide, crush, chew, or dissolve this medication before swallowing it.

When taking this medication, you may see something in your stool that looks like a tablet. This is the empty shell after the medication has been absorbed by your body.

Many things can affect the dose of a medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important to take this medication exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature and keep it out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Do not take desvenlafaxine if you:

  • are allergic to desvenlafaxine, venlafaxine, or any ingredients of the medication
  • are currently taking an MAO inhibitor (e.g., phenelzine, tranylcypromine) or have taken one in the last 14 days (MAO inhibitors should not be taken until at least 1 week after stopping treatment with desvenlafaxine)

What side effects are possible with this medication?

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
  • anxiety
  • chills
  • constipation
  • decreased appetite
  • diarrhea
  • difficulty concentrating
  • difficulty urinating
  • dilated pupils
  • dizziness
  • drowsiness
  • dry mouth
  • headache
  • hot flushes
  • increased sweating
  • irritability
  • nausea
  • nervousness
  • rash
  • ringing in the ears
  • sexual problems (such as decreased sex drive, difficulty getting an erection, or difficulty having an orgasm)
  • taste changes
  • tingling, burning, or prickly sensations
  • trembling or shaking
  • trouble sleeping
  • tiredness
  • vision changes
  • vomiting
  • weakness
  • weight changes
  • yawning

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

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

  • cold hands and feet
  • dizziness when rising from standing or lying position
  • fainting
  • increased blood pressure
  • increased cholesterol or triglyceride levels
  • new or worsened emotional or behavioural problems
  • pounding or fast heartbeat
  • signs of bleeding (e.g., bloody nose, blood in urine, unusual bruising,  bleeding gums, cuts that don't stop bleeding)
  • symptoms of increased pressure in the eyes (e.g., decreased or blurred vision, eye pain, red eye, swelling of the eye)
  • symptoms of low sodium levels in the blood (e.g., achy, stiff, or uncoordinated muscles, confusion, tiredness, weakness)
  • symptoms of mania (e.g., decreased need for sleep, elevated or irritable mood, racing thoughts)
  • symptoms of serotonin syndrome
    • confusion
    • fast heartbeat
    • hallucinations
    • restlessness
    • shaking
    • shivering
    • sudden jerking of muscles
    • sweating
  • uncontrollable movements of the body or face

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

  • seizure
  • signs of a serious allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)
  • symptoms of severely increased blood pressure: (e.g., chest pain, blurred vision, dizziness, excessive tiredness, headache, stronger or faster heart beat)

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.

Are there any other precautions or warnings for 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.

Abnormal bleeding: There have been some reports of abnormal bleeding associated with desvenlafaxine. The risk of bleeding may be increased by other medications that affect bleeding (e.g., ibuprofen, naproxen, acetylsalicylic acid [ASA], warfarin). If you notice unusual bleeding or bruising, contact your doctor right away. If you have a bleeding disorder, 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 desvenlafaxine may increase blood pressure. People with high blood pressure should have their blood pressure controlled before taking this medication. Your doctor will check your blood pressure regularly while you are taking this medication.

Bone fractures: Medications in the same class as desvenlafaxine have been reported to increase the risk for bone fractures. If you have osteoporosis or are at risk for developing osteoporosis, or have had a recent bone fracture, 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: This medication may increase cholesterol and triglyceride levels. Your doctor may monitor these levels while you are taking this medication. If you have high cholesterol or triglyceride levels, 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: People taking desvenlafaxine should not drive a car or perform hazardous tasks until they determine that this medication does not impair their ability to perform these tasks safely.

Eye conditions: Desvenlafaxine has been associated with dilation of the pupil. If you have elevated pressure in the eye or are at risk of developing narrow-angle glaucoma, your doctor will monitor your condition closely.

Heart and other blood vessel disease: If you have heart disease or blood vessel disease in the brain (e.g., history of a stroke), 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.

Kidney function: Reduced kidney function or kidney disease may cause this medication to build up in the body, causing side effects. If you have 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.

Low sodium levels: This medication may cause low sodium levels, especially for seniors, people who are dehydrated, and people taking diuretics (water pills). Contact your doctor if you notice symptoms of low sodium such as confusion, concentration or memory problems, weakness, or unsteadiness.

Lung problems: Rarely, some people taking this medication may develop certain lung problems or infections. These can become serious very quickly. If you notice any coughing, difficulty breathing, or chest discomfort while taking desvenlafaxine, see your doctor as soon as possible.

Mania or bipolar disorder: This medication may activate mania. If you have a history of mania or bipolar disorder, 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.

Narrowing or blockage of the gastrointestinal tract: This medication should not be taken by people who have narrowing or blockage of the gastrointestinal tract (esophagus, stomach, intestines) due to medical conditions such as "short gut" syndrome, cystic fibrosis, or inflammatory bowel disease (e.g., ulcerative colitis).

Seizures: As with other antidepressants, this medication may increase the risk of seizures. If you have had seizures in the past, 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 rare but potentially life-threatening condition called serotonin syndrome, especially when used with other medications that increase serotonin levels (e.g., sumatriptan, rizatriptan, tramadol, St. John's wort, sibutramine). Get immediate medical attention if you experience symptoms such as:

  • agitation
  • confusion
  • diarrhea
  • fast heart rate
  • fever
  • hallucinations
  • increased body temperature
  • lack of coordination
  • nausea
  • overactive reflexes
  • vomiting

Stopping the medication: Stopping this medication suddenly may lead to unwanted symptoms such as:

  • agitation
  • anxiety
  • confusion
  • diarrhea
  • dizziness
  • electric shock sensations
  • fatigue
  • headache
  • irritability
  • nausea
  • sleep disturbances
  • sweating

Although these symptoms usually go away without treatment, tell your doctor if you experience any of these symptoms. When this medication is stopped, it should be stopped gradually as directed by your doctor.

Suicidal or agitated behaviour: People taking antidepressants such as desvenlafaxine may feel agitated (restless, anxious, aggressive, emotional, trouble sleeping, and feeling not like themselves), or they may want to hurt themselves or others. These symptoms may occur within the first few weeks of starting this medication. If you notice any changes in mood, behaviours, thoughts, or feelings in yourself or someone who is taking this medication, contact a doctor immediately. Your doctor will monitor you closely for behaviour changes, especially at start of treatment or when your dose is increased or decreased.

Pregnancy: Newborns whose mothers take medications such as desvenlafaxine during the third trimester of pregnancy may experience complications that require prolonged hospitalization. These complications normally resolve over time.

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. Do not stop taking this medication without talking to your doctor. If this medication is stopped, it should be stopped gradually as directed by your doctor.

Breast-feeding: This medication passes into breast milk. If you are a breast-feeding mother and are taking desvenlafaxine, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding. If your baby experiences breathing problems, feeding problems, seizures, tense or overly relaxed muscles, jitters, or constant crying, contact your doctor as soon as possible.

Children: The safety and efficacy of using this medication have not been established for children less than 18 years of age. The use of this medication by children less than 18 years old may cause behavioural and emotional changes, such as suicidal thoughts and behaviour.

Seniors: Seniors may be more likely to experience side effects, especially increased blood pressure, with this medication than younger adults. Lower doses may be needed.

What other drugs could interact with this medication?

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

  • acetylsalicylic acid (ASA)
  • alcohol
  • antipsychotics (e.g., haloperidol, quetiapine, olanzapine, risperidone)
  • "azole" antifungal medications (e.g., fluconazole, ketoconazole, itraconazole)
  • axitinib
  • benzodiazepines (e.g., lorazepam, diazepam, clonazepam)
  • bromocriptine
  • cabergoline
  • cyclobenzaprine
  • desipramine
  • dextromethorphan
  • epinephrine
  • linezolid
  • lithium
  • nefazodone
  • norepinephrine
  • MAO inhibitors (e.g., tranylcypromine, phenelzine, selegiline)
  • midazolam
  • NSAIDs (e.g., ibuprofen, indomethacin, naproxen)
  • narcotic pain medications (e.g., codeine, morphine)
  • phenobarbital
  • pseudoephedrine
  • saxagliptan
  • sedating antihistamines (e.g., diphenhydramine, hydroxyzine)
  • serotonin antagonists (e.g., granisetron, ondansetron)
  • SSRIs (e.g., citalopram, paroxetine, escitalopram)
  • St. John's wort
  • sibutramine
  • simeprevir
  • tramadol
  • trazodone
  • tricyclic antidepressants (e.g., amitriptyline, imipramine)
  • triptan medications (e.g., naratriptan, rizatriptan, sumatriptan)
  • tryptophan supplements
  • venlafaxine
  • warfarin

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.