Venlafaxine: Dosage, Adverse Effects, Precautions, Interactions, Recommendations and Storage

It is a drug that is used to fight depression.

It has the effect of improving your mood and energy and can help restore interest in daily life.

Venlafaxine is listed as a serotonin-norepinephrine reuptake inhibitor (SNRI).

Its function is to restore the balance of serotonin and norepinephrine in the brain.


It should be ingested orally based on your doctor’s instructions, usually 2 to 3 times daily with food.

Dosage is determined by your medical condition and your reaction to treatment.

To decrease the risk of side effects, your doctor may order you to start using this medicine with a small, progressively increasing dose.

Follow your doctor’s instructions very carefully. To remember better, it is suggested to take it at the same time daily.


Do not stop taking the drug without discussing it with your doctor, as certain conditions could worsen when use is suddenly stopped.

You may also experience symptoms such as confusion, changing moods, headaches, exhaustion, changes in sleep, and instantaneous sensations similar to that of an electric shock.

You may need to reduce the dose gradually to lessen the side effects. See any new or worsening symptoms right away.

It may take several weeks for you to feel the benefit of this medicine. Contact your doctor if your condition persists or worsens.

Venlafaxine Adverse Effects

Venlafaxine may cause vomiting, drowsiness, dizziness, dry mouth, constipation, loss of appetite, blurred vision, nervousness, trouble sleeping, or unusual sweating.

Tell your doctor if any of these effects last or get worse immediately. Serious side effects are rare in users of this drug.

Venlafaxine is also likely to increase blood pressure.

Tell your doctor as soon as possible if you show any of the following unlikely but strong side effects:

  • Bruising or bleeding easily.
  • Little interest in sex.
  • Changes in sexual performance.
  • Muscle cramps or weakness
  • Tremors

Seek immediate and urgent medical attention if you develop any of these rare but serious problems that do not go away:

  • Difficulty breathing.
  • Pain in the chest area.
  • Strong headache.
  • Black or bloody stools.
  • Vomiting with the appearance of coffee grounds, pain, swelling, or redness of the eyes.
  • Dilated pupils, vision changes (such as seeing rainbows around lights at night).
  • Seizures

Venlafaxine can increase serotonin and rarely causes a relatively strong condition called serotonin syndrome or toxicity.

The danger increases if you take other medications that increase serotonin, so ideally, your doctor is aware of all the medicines you use.

Get immediate medical help if you show any of these symptoms:

  • Rapid heart palpitations.
  • Delusions
  • Loss of coordination
  • Strong dizziness
  • Intense vomiting or diarrhea.
  • Muscle contractions
  • Unforeseen fever
  • Unusual restlessness

An extreme allergic reaction to this drug is rare. However, see your doctor as soon as possible if you notice any symptoms of a severe allergic reaction, including:

  • Rashes
  • Itching or swelling (especially of the face, tongue, or throat).
  • Strong dizziness
  • Difficulty breathing.

This list of possible side effects is incomplete. If you see other products not mentioned above, contact your doctor as soon as possible.


Before using venlafaxine, tell your doctor if it or desvenlafaxine causes allergic reactions or if you are allergic to another drug.

This medicine may have passive components that cause allergic reactions or other complications.

Before using venlafaxine, show your doctor your medical history, especially if there are or have been cases of:

  • Bleeding problems
  • Personal or family history of glaucoma.
  • High blood pressure .
  • Heart problems.
  • High cholesterol.
  • Kidney diseases.
  • Liver diseases
  • Seizure disorder
  • Thyroid diseases.

Older adults are more exposed to side effects of this drug, especially dizziness when standing or when they have any bleeding.

Older adults may also be more likely to develop hyponatremia, and they are increased if they are taking diuretics.

Children may be more susceptible to the adverse effects of the drug, significantly decreased appetite and weight.

This drug should be used only when strictly necessary during pregnancy because there is a possible danger of harming an unborn baby.

Likewise, newborns of mothers who have used this drug in the last three months of pregnancy may strangely develop withdrawal symptoms, which could be:

  • Difficulty eating or breathing.
  • Seizures
  • Muscle hardness or persistent crying.

Tell the doctor immediately if you notice any or more of these symptoms in your newborn.

Do not stop taking this drug unless directed by your doctor because untreated mental or mood problems can be a severe conditions.

If you are planning a pregnancy, become pregnant, or think you may be, talk to your doctor about the benefits and dangers of using this medication during pregnancy.

This medicine passes into breast milk and may have unwanted effects on a nursing infant. Consult your doctor before beginning the breastfeeding process.

Interaction of venlafaxine with other drugs

Interactions with other medications can alter how venlafaxine works or increase the risk of substantial side effects.

Please list all the products you use (including prescription and non-prescription drugs, herbal products, and natural medicine) and show them to your doctor.

Do not start, interrupt, or modify the dosage of any drug in use without the prior consent of your physician.

Some products that can be taken together with this medicine include other medicines that can cause bleeding or bruising (including antiplatelet agents like clopidogrel, NSAIDs like ibuprofen/naproxen ‘ and blood thinners’ like dabigatran/warfarin).

Aspirin can increase the risk of bleeding when used with this drug.

However, if your doctor has directed you to use a small dose of aspirin to prevent a heart attack or stroke, you should continue taking it unless your doctor tells you otherwise.

Taking MAO inhibitors with this drug could cause a severe and possibly fatal interaction.

Try not to use MAO inhibitors such as isocarboxazid, linezolid, methylene blue, moclobemide, phenelzine, or procarbazine, among others, during treatment with this medicine.

All MAO inhibitors should be avoided for two weeks before and for at least one week after venlafaxine treatment to not interfere with its effect.

The danger of developing serotonin syndrome is increased if you are using other medications that increase the level of serotonin. Examples include street drugs such as:

  • MDMA (ecstasy).
  • Grass of San Juan.
  • Some antidepressants (including SSRIs such as fluoxetine or paroxetine, other SNRIs such as duloxetine or milnacipran), and tryptophan. For a complete list, check with your doctor.

It is important to note that venlafaxine is very similar to desvenlafaxine. Do not use drugs with desvenlafaxine while using venlafaxine.

This medication may interfere with some laboratory tests (including urine amphetamine tests), possibly causing inaccurate or false results.

It is necessary that competent laboratory personnel and all your doctors know that you use venlafaxine.



If someone overdoses and shows severe symptoms, such as fainting or shortness of breath, call 911 or a poison control center.

Symptoms of an overdose can be severe drowsiness, seizures, fast heartbeat.

Notes:  Keep all medical and psychiatric appointments regularly.

Laboratory and medical tests (such as blood pressure and cholesterol) should be performed periodically to monitor your progress or check for side effects.

Missed dose

If you miss a dose, take it as soon as you remember. If it is too close to the time for the next dose, skip the missed dose and go back to your prescribed dosing schedule. Do not try to repeat the amount to make up for the one you missed.


Ideally, keep the medicine a room temperature away from light and moisture. Avoid storing them in the bathroom.

Keep the drug out of the potential reach of children and pets.

Do not flush the medicine down the toilet or flush it down the drain unless directed by your doctor or other professional.

Dispose of this product properly when it has expired or is no longer used.