Precautions and Warnings for Venlafaxine

Some Precautions and Warnings for Venlafaxine

Some venlafaxine precautions and warnings include:
  • Antidepressants (including venlafaxine) may increase the risk of suicidal thinking or behavior in children, teenagers, and adults (see Antidepressants and Suicide for more information). Therefore, if you notice any changes in symptoms or new symptoms while taking venlafaxine, talk with your healthcare provider immediately. Some of these symptoms include anxiety, hostility, agitation, panic, restlessness, hallucinations, extreme hyperactivity, and suicidal thinking or behavior (see Effexor and Suicide for more information).
  • Before prescribing venlafaxine for depression, your healthcare provider should make sure that you do not have bipolar disorder (instead of depression). Sometimes, the symptoms of bipolar disorder and depression are very similar, and venlafaxine can cause problems in people with bipolar disorder.
  • In previous studies, venlafaxine was shown to slightly increase blood pressure and heart rate. Your healthcare provider should monitor your blood pressure and heart rate while you are taking venlafaxine.
  • Antidepressants can cause a group of dangerous symptoms known as serotonin syndrome. Taking venlafaxine with other medications that affect serotonin can increase your risk of serotonin syndrome. These other medications can include other antidepressants, triptans (migraine medications), and several other medications (see Drug Interactions With Venlafaxine for more information). Contact your healthcare provider immediately if you have any possible symptoms of serotonin syndrome, including:


    • Confusion
    • Seeing or hearing things that are not really there (hallucinations)
    • Fast heartbeat (tachycardia)
    • Feeling faint
    • Fever
    • Sweating
    • Muscle spasms
    • Difficulty walking
    • Diarrhea.
  • Your healthcare provider should monitor your closely if you have glaucoma (a condition of the eye) while you are taking venlafaxine, as venlafaxine may make glaucoma worse.
  • Venlafaxine can cause anxiety, nervousness, and insomnia. Tell your healthcare provider if you experience these symptoms while taking venlafaxine.


  • Venlafaxine may increase the risk of bleeding or bruising. This is probably most dangerous in people who already have a bleeding disorder or who take other medications that increase the risk of bleeding.


  • Venlafaxine can cause a loss of appetite and weight loss. Usually, weight loss is small. However, it is possible to lose large amounts of weight while taking venlafaxine (see Effexor and Weight Loss).
  • Venlafaxine can cause seizures or high cholesterol, or may increase your risk of bleeding. Let your healthcare provider know if you have a seizure or if you notice any unusual bleeding (such as unusual bruising or blood in the stool) while taking venlafaxine.


  • Venlafaxine may increase your risk for certain lung problems. Be sure to let your healthcare provider know right away if you have signs of lung problems, such as difficulty breathing, coughing, or chest pain.


  • Since venlafaxine is removed from the body using the liver and kidneys, you may need a lower venlafaxine dosage if you have liver or kidney problems.
  • Venlafaxine can interact with certain other medications (see Drug Interactions With Venlafaxine).
  • You should talk with your doctor about whether you should avoid alcohol while taking venlafaxine (see Alcohol and Effexor).
  • If you are elderly or are taking a diuretic, venlafaxine could cause low salt levels in the blood (hyponatremia). Salt levels generally return to "normal" when venlafaxine is discontinued.
  • If you are stopping venlafaxine, you should be monitored by a healthcare professional for venlafaxine withdrawal symptoms. If you do develop any symptoms of venlafaxine withdrawal -- such as irritability, anxiety, confusion, headache, lethargy, or insomnia -- your healthcare provider may slow down the rate at which the venlafaxine is stopped (see Venlafaxine Withdrawal).


  • This medication can cause false positives on some urine drug tests for phencyclidine (PCP) or amphetamines. If this happens, more specific tests can be done to confirm (or deny) the results of the initial test. 


  • Venlafaxine may affect your ability to perform complex tasks requiring mental and motor skills. Therefore, it is recommended that you become accustomed to its effect on you before performing activities that require mental or motor concentration (such as driving a car or operating machinery). Taking venlafaxine with alcohol or other medications that cause drowsiness can increase this effect.
  • Venlafaxine is considered a pregnancy Category C medication. This means that venlafaxine may not be safe to use during pregnancy. Talk with your healthcare provider about the risks and benefits of using venlafaxine during pregnancy (see Effexor and Pregnancy for more information).
  • Venlafaxine passes through breast milk. Therefore, if you are breastfeeding or plan to start breastfeeding, be sure to talk with your healthcare provider about using venlafaxine (see Effexor and Breastfeeding).


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