Pristiq vs Effexor: Similarities and Differences

By Sabina Rebis, MD
Medically reviewed checkmarkMedically reviewed
May 24, 2022

Depression and anxiety can leave us feeling helpless, uncertain, nervous, and with low energy. 

These mental health conditions affect millions of Americans daily.

Although depression or general anxiety can get in the way of your day to day life, there are a variety of treatment options that may help ease symptoms.

Those  who are considering going down the route of starting a medication have a variety of choices.

Here, we’ll discuss two antidepressants: Pristiq and Effexor. 

In this article, we’ll go over what Pristiq is, what Effexor is, how they are similar, and how they’re different.

We will also discuss some precautions that should be taken with each drug, their side effects, and talk about when it may be time to speak with your doctor about your depression. 

What is Pristiq?

Pristiq (or desvenlafaxine as it is referred to in its generic form) is an antidepressant.

It is often prescribed for major depressive disorder and can also be used to treat anxiety.

Desvenlafaxine belongs to a class of medications known as SNRIs (selective serotonin and norepinephrine reuptake inhibitors), and can help manage mood levels, which can help with depression or anxiety. 

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Pristiq uses

Pristiq is prescribed to treat symptoms of both depression and anxiety.

While mostly indicated for major depressive disorder, Pristiq may be prescribed off label for general anxiety disorder, panic attacks, major depressive disorder, social anxiety disorder, and can be used as a  mood stabilizer.

It can help with symptoms such as prolonged sadness, loss of interest in activities, trouble sleeping, and generally decreased energy levels. 

How Pristiq works

Pristiq is part of a class of drugs known as SNRIs, selective serotonin and norepinephrine reuptake inhibitors.

SNRIs work on  the neurotransmitters serotonin, and norepinephrine to help regulate mood.

They can increase  the available levels of these chemicals in your brain and block their reabsorption, thus helping to improve  general mood. 

What is Effexor?

Effexor (known as venlafaxine in its generic form) is a medication used to treat a variety of anxiety disorders, as well as clinical depression.

It helps ease symptoms like sadness, hopelessness, guilt, and lack of energy or joy in activities.

It can also increase energy levels and decrease physical symptoms of anxiety, like upset stomach, jitters, and shaking. 

Effexor uses

Effexor is used to treat a variety of anxiety disorders, including general anxiety, panic disorder, and social phobia disorder.

It can also act as a  mood stabilizer and is prescribed to treat major depressive disorder.

It has  been used to help treat symptoms of PTSD, migraines, bipolar depression, ADHD, nerve pain as associated with diabetes, as well as hot flashes caused by menopause and chemotherapy. 

How Effexor works

Like Pristiq, Effexor is an SNRI, so it prevents the reuptake of the neurotransmitters serotonin and norepinephrine increasing their availability in the brain.

These neurotransmitters help regulate mood and energy levels.

When these levels are too low, you can experience symptoms of anxiety and depression.

By increasing their available levels in the brain, Effexor — and all SNRIs — help to decrease symptoms of depression or anxiety. 

How are They Similar?

Some studies refer to venlafaxine as the “parent drug” of desvenlafaxine, which is to say that Effexor and Pristiq are quite similar in their function and treatment applications.

Venlafaxine is metabolized to desvenlafaxine in the body.

Drug class

Both Effexor and Pristiq are in a drug class known as SNRIs.

As we’ve already discussed, SNRIs help manage the levels of serotonin and norepinephrine available in the brain.

They are a type of antidepressant that are also commonly prescribed for anxiety disorders, as well as depression.

SNRIs are often prescribed as an alternative to SSRIs, which are usually the first line of treatment tried for depression and anxiety.

Effectiveness at treating depression

Clinical studies show that Pristiq is nearly as effective as Effexor in treating symptoms of depression.

It is important that you talk to your doctor and talk through your options thoroughly with them.

You should take into consideration side effects and other lifestyle choices. 

Side effects

Side effects may be similar for venlafaxine and desvenlafaxine, as studies demonstrate.

Most common side effects for both include nausea, vomiting, diarrhea, constipation, decreased appetite, sleepiness, dry mouth, and sweating.

Many anti-depressants also have possible sexual side effects, which include reduced libido or trouble achieving or maintaing erections. 

How are They Different?

While Pristiq and Effexor are within the same drug class and sometimes prescribed to treat similar conditions, there are a few differences.

They are approved to treat slightly different conditions, and their dosing is different. 

Conditions treated

While Pristiq is approved only for the treatment of major depressive disorder, off-label it is  prescribed for other uses, like treating anxiety.  

ConditionPristiqEffexor
Major Depressive DisorderYesYes
Generalized Anxiety DisorderOff-labelYes
Social Phobia DisorderOff-labelYes
Panic DisorderOff-labelYes
Migraines & Tension HeadachesOff-labelYes
Nerve painNot enough researchYes
PTSDOff-labelYes

Dosage

When starting Effexor, your doctor will usually start at 37.5 mg per day before increasing to the standard minimum dose of 75 mg per day. Most people settle at around 150 mg dose daily.

The reason for  starting off with a low dose is to prevent any unwanted side effects, which may present in the early stages of taking the medication. 

Pristiq is prescribed at a starting dose of 50 mg per day, and there is no evidence that a greater dose is beneficial.

There is a lower dose of 25 mg per day for those wishing to wean up slowly or weaning off the drug. 

Pristiq Precautions

You should always tell your doctor about any other medications you are taking before beginning Pristiq as there may be a  risk of serious interaction.

It is important to take Pristiq as prescribed.

Stopping the medication suddenly can lead to serious side effects and withdrawal symptoms.

You should also talk to your doctor if you are or plan to get pregnant while taking Pristiq. 

Although uncommon, Pristiq and other SNRI antidepressants can also cause hypertension, or high blood pressure.

If you are at an increased risk for hypertension, consult with your doctor.

While allergic reactions are also rare, they are possible.

If you experience symptoms of an allergic reaction, including swelling of airways and difficulty breathing, call 911 immediately. 

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Effexor Precautions

In addition to familiarizing yourself with the possible side effects of the medication, it is essential to tell your doctor about all other medications and allergies you have.

You should avoid alcohol and operating heavy machinery when taking the medication, as Effexor can make you drowsy.

Discuss with your doctor if you are pregnant or breastfeeding. 

Effexor, and other major antidepressants, can increase your risk of bleeding, especially if you are on blood thinners or taking aspirin.

Consult with your healthcare provider if you are taking or prescribed SNRI antidepressants and blood thinners. 

Although it’s rare, medications that increase serotonin, like Effexor and Pristiq, can cause serotonin syndrome.

This is a very serious condition that requires immediate medical attention.

Seek medical attention if you experience: hallucinations, fever, sweating, rapid heart rate, uncontrolled muscular stiffness or twitching, unusual agitation or restlessness, or loss of coordination.

If symptoms of your depression don’t improve after several weeks of using these medications, check back in with your doctor.  

When to see a Doctor for Depression

Depression symptoms can get in the way of your daily life, and leave you feeling helpless, unhappy, and stressed for prolonged periods of time.

There are a variety of reasons you may develop depression.

If depression symptoms affect your quality of life or last more than two weeks, speak with your doctor about your options for treatment of depression.

Frequently Asked Questions

Is Effexor or Pristiq better for anxiety?
Both Effexor and Pristiq may be effective for treating anxiety, but Pristiq is not FDA approved to treat anxiety disorders. It is still sometimes prescribed off-labeland has shown to be as effective as Effexor.
What is the difference between Effexor and desvenlafaxine?
Effexor and desvenlafaxine have very similar pharmacological make-ups. The main difference is the dosing and cost of the medication. Effexor is prescribed in higher doses than desvenlafaxine. Side effects may vary from person to person between the two as well.
Is there a better antidepressant than Effexor?
Effexor is an SNRI, which may be on occasion more effective at treating depression than SSRI options. Studies show that amongst drugs within a similar pharmaceutical family, there is not necessarily a “better” option for an antidepressant than Effexor.
Which SNRI has the least side effects?
Side effects will vary from person to person. The best way to know which SNRI is best for you is to discuss with your doctor and follow medical advice depending on your concerns and other medication you may be taking.

K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

Sabina Rebis, MD

Dr. Sabina Rebis is a board certified family medicine physician with over 5 years of primary care and urgent care experience.