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Drug Class: Commonly Known As: Category:
Serotonin and Noradrenaline Reuptake Inhibitors (SNRI) efexor, efexor xl Adult

venlafaxine - What is it for

​This medicine belongs to a class of antidepressants known as the Serotonin and Noradrenaline Reuptake Inhibitors (SNRIs).

It is used to treat conditions such as:

  • Low mood (depression)
  • Anxiety
  • Panic attacks

It may be given to you for other reasons. Do check with your doctor what you are taking this for.

venlafaxine - Side Effects, Precautions, and Contraindications

What side effects can venlafaxine cause?

Potential side effects

All medicines may cause side effects. However, many people do not experience them.

Most of the side effects listed here will improve with time. Speak with your doctor or pharmacist if they persist, become bothersome or worsen.


Side effectsWhat to do about it
Poor appetite, nausea, vomitingTake this medicine after meals. Eat small but frequent meals to minimize bloating after a meal. Avoid food that is too rich, spicy or has strong smells.
DiarrhoeaMake sure you remain well hydrated by drinking plenty of water

Increase your intake of fluids and include more fibre (vegetables and fruits) in your diet. Incorporate some exercise in your daily routine.

Consult your doctor or pharmacist if you require any laxatives.

Dry mouthSip water regularly. Sucking on sugar-free sweets or ice chips may help alleviate symptoms. Avoid caffeine as it may worsen dry mouth.
HeadacheConsult your doctor or pharmacist if you need any painkillers

Do not drive or operate any machinery until you have experienced how this medicine affects you.

Discuss with your doctor if you can take your medicine at a different time of the day. 

DizzinessGet up slowly from a lying or sitting position
Difficulty sleeping

Avoid daytime naps. Limit caffeine intake. Keep a regular sleeping schedule. Instead of looking at electronic screens before bedtime, choose other relaxing activities such as reading a book or listening to calm music.

Discuss with your doctor if you can take your medicine at a different time of the day. 

Nervousness and anxiousnessUsually occurs at the beginning of treatment and subsides with time. Avoid caffeine intake, and try to maintain a regular and healthy diet and sleeping schedule. If symptoms persist and/or do not improve consult your doctor.
Reduced sexual drive or abilityConsult your doctor if it becomes bothersome
Increased blood pressureDiscuss with your doctor on the monitoring of blood pressure


Serious side effects

Seek medical help as soon as possible if you have any of the following signs or symptoms.

  • Allergy such as rashes, swelling of lips/face/throat, difficulty breathing
  • A condition known as Serotonin Syndrome may occur rarely. Symptoms of serotonin syndrome include but are not limited to confusion, agitation, hallucinations, tremor, shivering and shivers. Consult your doctor if any unusual symptoms arise while taking this medicine.
  • In rare cases, a severe increase in blood pressure or altered heart rhythm may occur. Seek medical attention as soon as possible if you experience symptoms such as severe headache, chest pain, shortness of breath, dizziness or irregular heart beat/ palpitations in the heart.
  • If there is any worsening of your existing psychiatric condition/behavior or the emergence of new psychiatric conditions including thoughts of self-harm.

Take note that the side effects listed here are not exhaustive. Do seek medical attention if you have other symptoms that you think may be related to the medicines.


Before taking venlafaxine, what precautions must I follow?

​What do I need to tell my doctor before I take this medicine?

  • Drug allergies
  • Pre-existing medical conditions such as fits (seizures), bipolar disorders or mania (unusually high or excited mood, being much more active or having more energy than usual), low sodium levels, hypertension and heart problems.
  • Whether you are taking any other medicine, supplements or traditional medicines. Some of them may affect how this medicine works.
  • If you have taken any other antidepressants in the last 2 weeks

For women: Tell your doctor if you are pregnant or breast-feeding or have plans to become pregnant. If you are pregnant and/or breastfeeding, your doctor would have discussed the potential benefits and side-effects with you but should you have further questions or concerns, do consult your doctor.

What food or medicine must I avoid when I take venlafaxine?

​Avoid alcohol while taking this medicine. If you intent to take any over the counter medicine, supplement, traditional Chinese medicine or herbal preparation consult your doctor/pharmacist to ensure it is safe to take with venlafaxine.


venlafaxine - Dosage and How to Use

How should venlafaxine be used?

​Oral extended-release tablet or capsule:

Take this medicine exactly as prescribed by your doctor. Follow the instructions on the medicine label or as advised by the pharmacist.

Take it with or after food, at the same time of day. Swallow Venlafaxine whole; do not chew, crush or break the tablet/capsule.

This medicine may not have an effect immediately. It may take up to a few weeks before this medicine can exert its full effects. Continue taking it regularly to benefit from it.

Do not stop taking this medicine even after you feel better. Your symptoms may return if this medicine is stopped too early. Check with your doctor on the duration of treatment that is suitable for you.

Do not stop taking this medicine abruptly or change the dose without consulting your doctor. You may experience unpleasant side effects if it is stopped suddenly.

Avoid taking alcohol while you are on this medicine.

What should I do if I miss a dose?

​Take the missed dose as soon as you remember. However, if it is close to the time for your next dose, skip the missed dose and take the next one at your usual timing.

Do not take 2 doses at the same time or extra doses.

What should I do if I overdose?

​If you take more doses then prescribed by your doctor consult a doctor/healthcare professional immediately.


venlafaxine - Handling and Storage

How should I handle venlafaxine safely?

How should I store venlafaxine?

Keep away from children;#Keep in a cool, dry place, away from direct sunlight;#Store at room temperature;#

How should I dispose of venlafaxine safely?

​Discard any unused or expired medicine. Check with your pharmacist if you are unsure how to safely discard your medicines.

venlafaxine - Additional Information

​What are the things I need to know or look out for while on taking this medicine?

  • Avoid driving or any other activities that requires concentration until you see how this drug affects you.
  • Inform your other healthcare professionals that you are on this medicine as well.
  • Discuss with your doctor or pharmacist before you take any other medicine or natural products.
  • Do not share your medicines with others.
  • Consult your doctor or pharmacist if you have any questions about your medicines.
  • Tags: Venlafaxine
  • Updated on Tuesday, November 13, 2018
  • Article contributed by Changi General Hospital Changi General Hospital

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