Disclaimer: None of the information in this article constitutes medical advice, and is just the opinion of the writer(s) and published for informational purposes only. We recommend that patients follow their doctor’s guidance in regard to prescription medication.
Pristiq is a prescription antidepressant medication that’s an SNRI, or a serotonin and norepinephrine reuptake inhibitor. The generic name for Pristiq is desvenlafaxine, and we will use these terms interchangeably throughout this article because they refer to the same active ingredient.
In this article we’ll review the medical research on Pristiq, as well as the documented side effects, to determine if it’s likely to be a safe and effective treatment for depression. We’ll also highlight a novel antidepressant that patients may want to consider as an alternative.
Does Pristiq Work?
Pristiq is approved by the Food and Drug Administration (FDA) to treat depression, which means it’s likely to work on average.
A clinical trial published in the CNS Spectrums medical journal found that Pristiq was effective for patients with major depressive disorder. Most clinical trials on pharmaceutical drugs for depression use a patient population with major depressive disorder because this condition is more difficult to treat than mild or moderate depression with lifestyle changes.
Researchers in the trial measured patient scores on the Hamilton Depression Rating Scale (HAM-D), which tracks patient responses across a wide variety of symptoms associated with depression, such as insomnia and loss of sex drive.
The depressed patients taking Pristiq had their depression significantly reduced based on the HAM-D scoring. The average score was over 20 at the start of the trial and under 10 at the end of the trial, representing a decrease in depression symptoms of over 50%.
A meta-study was published in 2010 evaluating the efficacy of Pristiq for patients with major depressive disorder. This study analyzed results from 3 individual medical trials on the drug.
The study authors concluded that Pristiq was safe, effective and tolerable for depressed patients and improved their condition. Remission rates were around 10% higher in the groups taking Pristiq compared to the groups taking a placebo pill. Remission is defined as an extended period free of any major depressive symptoms.
A more recent medical study evaluated the effects of Pristiq on cognitive function related to work-related tasks in patients who were depressed and employed. The medication was not effective at improving neurocognitive function or measures of work function.
We can conclude from the available research that Pristiq is effective at improving depression, but may not be effective at improving depression-related impairment of cognition.
How Does Pristiq Work?
As stated in the intro, Pristiq is in a drug class called SNRIs, or serotonin and norepinephrine reuptake inhibitors. According to StatPearls, which is the largest free medication database maintained by the U.S. government, Pristiq is 10 times more selective for serotonin than norepinephrine.
This class of drugs delays the body’s processing of neurotransmitters serotonin and norepinephrine which have significant effects on mood. In Pristiq’s case, it has more of an effect on serotonin than norepinephrine based on the above-linked research review.
By blocking normal processing of these neurotransmitters, the drug causes an artificial increase in their circulating levels, which can improve mood and relieve symptoms of depression.
It hasn’t been conclusively proven that patients with depression have lower levels of these neurotransmitters than non-depressed patients, but this is the suggested mechanism of action.
Patients curious about Pristiq may want to read our Effexor reviews article, because that medication is another SNRI that is chemically similar to Pristiq.
Pristiq Side Effects
Pristiq is required by the FDA to publish a “black box” warning label, which references a risk of severe side effects. The black box warning for Pristiq indicates an increased risk of suicidal thinking and behavior in children, adolescents and young adults.
A medical trial published in the Current Medical Research and Opinion journal provides some more side effect data. About 5% more patients withdrew from the study because of adverse effects in the groups taking Pristiq than the group taking placebo. No one died in the study.
The most common side effect reported was dizziness, which occurred 8% more often than in those taking placebo, dry mouth which occurred 9% more often than in those taking placebo and constipation which occurred 7% more often than in those taking placebo.
Most of the common side effects of Pristiq seem relatively mild and standard for antidepressant drugs, but patients should definitely discuss the rare but serious risks of suicidality with their doctor.
Should I Take Pristiq Generic?
The generic form of Pristiq is called desvenlafaxine. These two drugs contain the exact same active chemical compound.
Because generic and brand-name drugs are the same, we typically recommend that patients speak with their doctor about taking the generic version, because it’s often more cost-effective (even for those with health insurance).
A medical review of the comparative effectiveness of generic and branded drugs found that the generic versions were just as effective on average.
Pristiq is prescribed at multiple different doses, but there’s an interesting study on dosage that we want to highlight. A clinical trial compared the efficacy of Pristiq at 50 milligrams (mg) per day, and 100 mg per day.
Contrary to what you might expect, the drug was actually more effective at the lower dose. Patients in the 50 mg group had lower scores on the HAM-D depression scale than patients in the 100 mg group at the end of the trial.
Since drugs often have a higher risk of side effects at higher doses, this trial suggests that taking Pristiq at 50 mg, at least as a starting dose, may be a more logical decision than taking the drug at 100 mg.
The StatPearls resource linked to earlier in this article details that the typical starting dose of Pristiq for adults is 50 mg, but the drug is also available at 25 mg and 100 mg doses.
Pristiq Withdrawal Symptoms
Like many antidepressant pharmaceutical medications, Pristiq does have a risk of uncomfortable withdrawal symptoms.
A research review published in 2009 documented these symptoms in order of occurrence. The most common withdrawal symptoms were similar to the most common Pristiq side effects: dizziness, nausea, headache and irritability.
Patients taking higher doses experienced worse withdrawal symptoms on average. After week 3, patients withdrawing from a 400 mg/day dose were still experiencing withdrawal symptoms around 100% more severe than patients withdrawing from a 100 mg/day dose.
Withdrawal symptoms can be mitigated with proper tapering, which means a strategic lowering of dose rather than stopping medication all at once. This is why it’s so important for patients to speak with their doctor prior to discontinuing medication. Even if the patient is set on quitting the medication, their doctor can help them taper off safely based on research standards which reduce withdrawal symptoms.
Pristiq Vs. Effexor
Both Pristiq and Effexor are commonly prescribed for antidepressant effect, but Effexor is also approved to treat other conditions like anxiety and mood disorders.
In terms of efficacy for treating depression, a medical trial evaluated which drug was superior. The researchers compared results from various clinical trials and concluded that the drugs had similar efficacy, which isn’t surprising given that they’re so chemically similar. The active ingredient in Pristiq is a metabolite of the active ingredient in Effexor.
Pristiq reduced depression scores by a small amount more than Effexor in the medical review, but not to a statistically significant degree. Pristiq also caused fewer patients to experience nausea as a side effect.
Because the drug appears slightly more effective and seems to have a slightly more favorable side effect profile, we would recommend that patients speak with their doctor about Pristiq over Effexor.
Pristiq for Anxiety
Pristiq isn’t typically prescribed to treat anxiety alone, but there is some medical research on its effects on anxiety in depressed patients.
A meta-study published in the CNS Spectrums journal analyzed results from 9 individual medical trials on Pristiq to examine its effects on anxiety.
Study participants taking Pristiq had significantly reduced anxiety on average at the end of the trials than at the beginning. Anxiety was 14% lower in those taking Pristiq than those taking placebo.
Another medical study showed similar results. Depressed patients taking Pristiq had reduced anxiety significantly by the end of the trial.
These studies suggest that Pristiq may be an effective option for patients with both depression and anxiety. They don’t prove that Pristiq is effective for non-depressed patients suffering from anxiety, because the patient populations from both studies were depressed.
We can’t locate any medical research suggesting that Pristiq is effective as a standalone treatment for anxiety in patients who are only diagnosed with anxiety but not depression.
Ketamine is a drug that has been studied recently for its use in treating depression. As we outlined in our ketamine therapy review article, there is some promising research on this compound but it should only be used in a clinical setting. It is not safe to use recreationally, and we don’t advise such use.
A clinical trial published in the American Journal of Psychiatry found that ketamine therapy was more effective than a leading antidepressant drug. Patients in the trial received 3 weekly IV infusions of ketamine over the course of two weeks.
A ketamine nasal spray was recently approved by the FDA for treatment of depression when used as an adjunctive treatment to an oral antidepressant.
The long-term safety of ketamine is still yet to be proven, and it’s not legal for medical use in all U.S. states, so it’s important for patients to do research before considering a clinic which offers this type of therapy.