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Effexor and Effexor XR (Venlafaxine)

Bipolar Medications Library


Updated June 16, 2014

Effexor - generic venlafaxine - is an antidepressant that is also sold in an extended-release form as Effexor XR. Effexor is not chemically related to the SSRIs (such as Prozac [fluoxetine] and Zoloft [sertraline]) or tricyclics (such as Elavil [amitriptyline]). It appears to work by inhibiting the reuptake of serotonin, norepinephrine and (weakly) dopamine in the central nervous system. These neurotransmitters play a key role in determine a person's mood (see Messengers of the Brain). The extended release form, Effexor XR, is also prescribed for generalized anxiety disorder.

Warnings for Effexor and Effexor XR

The most important thing to know before taking Effexor is that it must not be used in combination with another type of antidepressants called MAO inhibitors or MAOIs (for example, Nardil [Phenelzine], Marplan [isocarboxazid] and Parnate ). Serious and even fatal complications may result from such a combination. In addition, wait 14 days after discontinuing the MAOI before starting Effexor or Effexor XR, and wait 7 days after discontinuing either form of Effexor before starting an MAOI.

Effexor Withdrawal

Dr. Ivan Goldberg recommends starting at low dose and building up gradually, and also warns against stopping use of Effexor abruptly. Withdrawal syndrome, which may be severe and prolonged, can occur even if the medication is tapered off. Symptoms may include:
  • headaches,
  • nausea,
  • dizziness,
  • unstable moods,
  • gastrointestinal upset,
  • recurrence of depression,
  • bizarre dreams,
  • paraesthesiae (abnormal sensations of burning, prickling, tingling, etc.), or
  • auditory hallucinations.

Effexor / Effexor XR Side Effects

While the registered side effects list for Effexor / Effexor XR is not long, some sources say many more side effects exist that are not registered. Therefore, it is very important to monitor your physical and mental condition closely while you are taking this drug.

List of Effexor's Registered Side Effects

Other Precautions Regarding Effexor / Effexor XR

Make sure your doctor knows your complete medical history. Effexor may not be a good choice if you have:
  • Brain disease or damage, or mental retardation, or a history of seizures - the risk of seizures may be increased

  • Heart disease or high or low blood pressure - venlafaxine may make these conditions worse

  • Kidney disease or liver disease - higher blood levels of venlafaxine may occur, increasing the chance of side effects; your doctor may need to adjust your venlafaxine dose

  • A history of mania - the risk of developing mania may be increased; obviously this is very important for bipolar patients to watch for

Other Important Facts About Effexor / Effexor XR

  • It may take several weeks for the effects of this medication to kick in.

  • Take as directed, with food, and do not break, crush or chew tablets or open the capsules.

  • If you miss a dose, do not take a double dose to make up.

  • Be cautious for side effects when taking any over-the-counter medications with Effexor or Effexor XR.

  • Health Square indicates that elderly persons or those with liver disease or high blood pressure should check with their physicians before combining Effexor with Tagamet (cimetidine).

  • Health Square (above) also reports that this medication may cause water retention in the elderly.

  • Nausea is the most commonly reported side effect. The manufacturer says this will usually diminish within two weeks.

  • Animal test results show that use of Effexor while pregnant or nursing may not be wise, and there have been no controlled studies to date in pregnant women.

  • Effexor and Effexor XR may cause weight loss; this weight loss is usually small, but if a large weight loss occurs, it may be harmful in some patients.
Effexor and Effexor XR have a good remission rate for depression that resisted other antidepressant medications, but the dropout rate due to side effects, according to the manufacturer (Wyeth-Ayerst), is fairly high: 19% for Effexor, and 11% for Effexor XR.

The Bottom Line or Effexor / Effexor XR

Effexor may be a good choice for treatment-resistant depression or depression with anxiety. When taking either form of this medication, however, report anything unusual to your doctor, as side effects have been reported that are not listed in the patient insert. These additional side effects are said to be rare, but it's best to be cautious.

Disclaimer: This profile is not intended to be all-inclusive or to replace information provided by your doctor or with the prescription from the manufacturer.

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