Pristiq dosage, forms, and strengths

Pristiq is a brand-name antidepressant available by prescription only. The active ingredient, desvenlafaxine, is an SNRI or “serotonin-norepinephrine reuptake inhibitor.” Pristiq works by adjusting the chemical balance of two neurotransmitters within the brain, serotonin and norepinephrine, which can help relieve symptoms of depression. People prescribed Pristiq will take a single extended-release tablet daily for several months to treat their depression.

Pristiq forms and strengths

Pristiq and its generic version, desvenlafaxine, come in only one dosage form.

• Extended-release tablets: 25 mg, 50 mg, 100 mg

Pristiq dosage for adults

The U.S. Food and Drug Administration (FDA) approves Pristiq for the treatment of major depressive disorder in adults. Healthcare professionals sometimes use Pristiq off-label to relieve the vasomotor symptoms of menopause, such as hot flashes and night sweats. Pristiq is safe for most adults to take. The only exceptions are people allergic to desvenlafaxine or venlafaxine (brand name Effexor) or who have taken a monoamine oxidase inhibitor (MAOI) medicine within the previous 14 days.

Check our best Pristiq prices

Pristiq dosage for major depressive disorder

Major depressive disorder (MDD) is diagnosed when someone shows symptoms of depression persistently for two weeks or longer. Desvenlafaxine, the active ingredient in Pristiq, increases the levels of norepinephrine and serotonin in the brain. These two chemicals pass signals between nerves in the brain, so activity in parts of the brain increases, relieving symptoms of depression.

Pristiq extended-release tablets are taken once daily at about the same time each day. The depression symptoms will not improve immediately. It may take several weeks of daily Pristiq doses before people feel better. It may take months for the depression to remit completely. Therapy typically lasts for six months or longer to prevent relapse.

• Standard adult dosage for major depressive disorder: 50 mg taken once per day

• Maximum adult dosage for major depressive disorder: 400 mg per day

Pristiq dosage for menopause symptoms

Pristiq is not FDA-approved as a menopause treatment. However, both SSRIs (paroxetine, citalopram, and escitalopram) and SNRIs (venlafaxine, desvenlafaxine, and duloxetine) may be effective at treating the vasomotor symptoms of menopause such as hot flashes and night sweats. Research has shown that these five drugs decrease the incidence of hot flashes by 24% to 69% compared to placebo and reduce the severity of hot flashes by 19% to 61%. However, only paroxetine is FDA-approved to treat menopause symptoms. The rest are used off-label.

Healthcare professionals will start women on a daily dose of 50 mg daily for menopause symptoms. They will increase the dose to as high as 150 mg daily if necessary. 

• Standard adult dosage for menopause symptoms: 50–150 mg taken once per day

• Maximum adult dosage for menopause symptoms: 400 mg per day

Pristiq dosage for children

The FDA has not approved the use of Pristiq in children.

Pristiq dosage restrictions

Dosage adjustments may be necessary for some people with liver or kidney problems. 

• Patients with renal impairment (kidney disease): 

  • Creatinine clearance greater than 30–50 milliliters (mL)/minute (min): 50 mg daily maximum

  • Creatinine clearance less than 30 mL/min: 25 mg taken once per day or 50 mg taken every two days 

• Patients with hepatic impairment (liver dysfunction): 50 mg daily maximum

How to take Pristiq

Pristiq tablets are taken once per day. There are no special instructions, so advice on taking Pristiq is straightforward:

• Take Pristiq as prescribed. Do not change the dose.

• Please read the Medication Guide that comes with this medicine. It includes warnings and side effects people should be aware of.

• Take Pristiq tablets once per day at the same time each day.

• Pristiq can be taken with or without food.

• Swallow the tablets whole with a glass of water. Do not crush, break, or chew them.

• You may later see what looks like a tablet in your stool. This is normal. It is just the empty shell of the tablet you took.

• Store Pristiq tablets in a closed container at room temperature.

Pristiq vs. Pristiq XR/ER: What’s the difference in doses? 

Pristiq is an extended-release tablet. It does not come in an immediate-release formulation.

How long does it take Pristiq to work?

It takes several weeks of daily Pristiq doses before people notice a significant mood improvement. In clinical studies, it took up to eight weeks for most participants to show significant improvements in mood and functioning, but people will often start feeling better before that.

How long does Pristiq stay in your system?

It takes the body 11 hours to eliminate half a dose of Pristiq. While this time varies from person to person, a single dose is completely eliminated from the system in a little over two days.

What happens if I miss a dose of Pristiq?

If a dose is missed, take it when remembered. Skip the missed dose if it’s almost time for the next dose. Never try to make up for a missed dose by taking extra medicine.

How long can you take Pristiq?

Pristiq is intended for long-term continual use. Therapy will last months, even a year, or longer if necessary. Clinical studies have not shown any adverse effects specifically due to the long-term use of Pristiq.

How do I stop taking Pristiq?

Do not stop taking Pristiq until talking to the prescriber. The dose will need to be gradually decreased to prevent withdrawal symptoms such as nausea, irritability, headaches, abnormal dreams, sweating, insomnia, and diarrhea.

People may need to discontinue Pristiq because of side effects or allergic reactions, but they will still have other options. Depression can be treated with a broad range of effective antidepressants, including tricyclic antidepressants, SSRIs, other SNRIs, monoamine oxidase inhibitors (MAOIs), atypical antidepressants, and drugs like Wellbutrin (bupropion).

What is the maximum dosage for Pristiq?

The maximum safe dosage is 400 mg per day, but healthcare professionals usually limit the daily dose for depression treatment to 50 mg. Clinical studies showed that higher doses, while safe, did not work any better than the 50 mg dose at improving depression symptoms. Doctors do use higher doses when necessary or to treat off-label conditions such as menopause or neuropathic pain.

Can you overdose on Pristiq?

Call a poison control center or get medical help if too much Pristiq is taken. If a Pristiq overdose is large enough, it could cause serious problems and even death. Symptoms of an overdose include sleepiness, vomiting, dilated pupils, racing heartbeats, and coma.

What interacts with Pristiq?

Pristiq has several drug interactions that may cause problems. 

Pristiq is never combined with monoamine oxidase inhibitors (MAOIs), a class of drugs that includes antidepressants (phenelzine, isocarboxazid, tranylcypromine), an antibiotic (linezolid), some Parkinson’s disease medications (rasagiline, selegiline, and safinamide), and a contrast dye used for medical imaging (methylene blue). MAO inhibitors must be discontinued for at least 14 days before taking Pristiq safely. Pristiq can’t be started again until it has been discontinued for at least seven days.

Serotonin syndrome is a serious complication of taking more than one drug that affects serotonin levels in the brain. Drugs that can cause serotonin syndrome when combined with Pristiq include:

• Other antidepressants

• SSRIs

• Anxiety medications

• Antipsychotic medications

• Migraine drugs called triptans

• The bipolar disorder drug lithium

• Narcotic pain relievers such as tramadol

• Amphetamines

• Anticonvulsants

• Anti-nausea drugs,

• The supplements St. John’s wort and tryptophan

Desvenlafaxine can also cause bleeding problems, so healthcare professionals are cautious about prescribing it with other drugs that cause bleeding, including nonsteroidal anti-inflammatory drugs (NSAIDs) and blood thinners such as warfarin.

What happens when you mix Pristiq and alcohol?

Avoid alcohol when taking Pristiq. It can worsen side effects like dizziness and drowsiness.

Is it safe to take Pristiq during pregnancy?

Healthcare providers are cautious about using Pristiq in pregnant women. Drugs like Pristiq can cause serious problems in newborns when they’re taken late in a pregnancy. Although Pristiq does not seem to harm the fetus, it can cause serious complications in pregnant women, including preeclampsia and postpartum hemorrhage.

Is it safe to take Pristiq while breastfeeding?

Healthcare providers can prescribe Pristiq to mothers who are breastfeeding, but there is a potential for problems. Desvenlafaxine is present in breast milk, and there’s a possibility that drug exposure can cause poor adaptation in a newborn. Mothers should monitor their infant for sedation when taking Pristiq.

What are the side effects of Pristiq?

The most common side effects of desvenlafaxine are nausea, dry mouth, dizziness, and sleepiness. The adverse effects that are most likely to cause people to stop taking Pristiq are nausea, constipation, dizziness, headache, vomiting, and trouble sleeping.

What are the serious side effects of Pristiq?

Though rare, Pristiq can cause serious problems, including:

• Suicidality

• Serotonin syndrome

• Increased risk of bleeding

• Seizures

• Discontinuation syndrome (withdrawal)

• Glaucoma

• Mania or hypomania

• Lung scarring (interstitial lung disease)

• Low sodium (hyponatremia)

• High cholesterol

• Elevated blood pressure.

What should I watch out for when taking Pristiq?

The FDA has mandated that Pristiq carry a boxed warning about the increased risk of suicidal thoughts in young adults and adolescents taking Pristiq. Anyone taking Pristiq or their caregivers should watch for signs of suicidality such as suicidal thoughts, talking about suicide, attempts at suicide, worsening depression, anxiety, agitation, panic attacks, insomnia, or unusual changes in behavior.

Sources

• Desvenlafaxine, Drugs and Lactation Database

• Desvenlafaxine, StatPearls

• Major depressive disorder, StatPearls

• Nonhormone therapies for vasomotor symptoms, Cleveland Clinic Journal of Medicine (2024)

• Pristiq drug summary, Prescriber’s Digital Reference (PDR)

• Pristiq extended release desvenlafaxine succinate tablet prescribing information, DailyMed (NIH National Library of Medicine)

• Pristiq HCP, Pfizer

• Pristiq, Pfizer