Pristiq is an antidepressant belonging to a group of drugs called selective serotonin and norepinephrine reuptake inhibitors (SNRIs). Desvenlafaxine affects chemicals in the brain that may be unbalanced in people with depression.

Pristiq is used to treat major depressive disorder.

Pristiq may also be used for purposes not listed in this medication guide.

Do not use Pristiq within 7 days before or 14 days after you have used an MAO inhibitor, such as isocarboxazid, linezolid, methylene blue injection, phenelzine, rasagiline, selegiline, or tranylcypromine.

People with depression or mental illness may have thoughts about suicide. Some young people may have increased suicidal thoughts when first starting a medicine to treat depression. Tell your doctor right away if you have any sudden changes in mood or behavior, or thoughts about suicide.

Do not stop using this medicine without first talking to your doctor.

Take Pristiq exactly as prescribed by your doctor. Follow all directions on your prescription label and read all medication guides or instruction sheets.

Take Pristiq with water at the same time each day, with or without food.

Swallow the tablet whole and do not crush, chew, or break it.

Your blood pressure will need to be checked often.

Tell your doctor if you have any changes in sexual function, such as loss of interest in sex, trouble having an orgasm, or (in men) problems with erections or ejaculation. Some problems can be treated.

It may take several weeks before your symptoms improve. Keep using the medication as directed and tell your doctor if your symptoms do not improve.

Do not stop using Pristiq suddenly, or you could have unpleasant symptoms (such as dizziness, vomiting, agitation, sweating, confusion, numbness, tingling, or electric shock feelings). Ask your doctor how to safely stop using this medicine.

Some tablets are made with a shell that is not absorbed or melted in the body. Part of the tablet shell may appear in your stool. This is a normal side effect and will not make the medicine less effective.

Store at room temperature away from moisture and heat.

You should not take Pristiq if you are allergic to desvenlafaxine or venlafaxine (Effexor).

Do not use Pristiq within 7 days before or 14 days after you have used an MAO inhibitor, such as isocarboxazid, linezolid, methylene blue injection, phenelzine, tranylcypromine, and others. A dangerous drug interaction could occur.

Tell your doctor if you also use stimulant medicine, opioid medicine, herbal products, or medicine for depression, mental illness, Parkinson's disease, migraine headaches, serious infections, or prevention of nausea and vomiting. An interaction with desvenlafaxine could cause a serious condition called serotonin syndrome. Ask your doctor before making any changes in how or when you take your medications.

To make sure you can safely take Pristiq, tell your doctor if you have any of these other conditions:

• heart disease, high blood pressure, high cholesterol, or a stroke;

• bipolar disorder (manic depression);

• depression, suicidal thoughts;

• liver or kidney disease;

• glaucoma;

• seizures or epilepsy;

• sexual problems;

• lung or breathing problems;

• a bleeding or blood clotting disorder; or

• low levels of sodium in your blood.

Some young people have thoughts about suicide when first taking an antidepressant. Your doctor should check your progress at regular visits. Your family or other caregivers should also be alert to changes in your mood or symptoms.

Ask your doctor about taking Pristiq if you are pregnant. Taking desvenlafaxine during late pregnancy could increase your risk of excessive bleeding just after you give birth, and may cause serious medical complications in the baby. However, you may have a relapse of depression if you stop taking your antidepressant. Tell your doctor right away if you become pregnant. Do not start or stop taking Pristiq without your doctor's advice.

If you are pregnant, your name may be listed on a pregnancy registry to track the effects of desvenlafaxine on the baby.

It may not be safe to breastfeed a baby while you are using this medicine. Ask your doctor about any risks.

Pristiq is not FDA-approved for use by anyone younger than 18 years old.

Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Desvenlafaxine may impair your thinking or reactions. Avoid driving or hazardous activity until you know how this medicine will affect you.

Ask your doctor before taking a nonsteroidal anti-inflammatory drug (NSAID) such as aspirin, ibuprofen, naproxen, Advil, Aleve, Motrin, and others. Using an NSAID with desvenlafaxine may cause you to bruise or bleed easily.

Avoid drinking alcohol.

Get emergency medical help if you have signs of an allergic reaction to Pristiq: skin rash or hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Tell your doctor right away if you have new or sudden changes in mood or behavior, including new or worse depression or anxiety, panic attacks, trouble sleeping, or if you feel impulsive, irritable, agitated, hostile, aggressive, restless, more active or talkative, or have thoughts about suicide or hurting yourself.

Call your doctor at once if you have:

• a seizure;

• easy bruising or bleeding (nosebleeds, bleeding gums), blood in your urine or stools, coughing up blood;

• blurred vision, eye pain or swelling, or seeing halos around lights;

• cough, chest discomfort, trouble breathing; or

• low blood sodium - headache, confusion, problems with thinking or memory, weakness, feeling unsteady.

Seek medical attention right away if you have symptoms of serotonin syndrome, such as: agitation, hallucinations, fever, sweating, shivering, fast heart rate, muscle stiffness, twitching, loss of coordination, nausea, vomiting, or diarrhea.

Common Pristiq side effects may include:

• dizziness, drowsiness, anxiety;

• increased sweating;

• nausea, decreased appetite, constipation;

• sleep problems (insomnia); or

• decreased sex drive, impotence, or difficulty having an orgasm.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Taking Pristiq with other drugs that make you drowsy can worsen this effect. Ask your doctor before using opioid medication, a sleeping pill, a muscle relaxer, or medicine for anxiety or seizures.

Many drugs (including some over-the-counter medicines and herbal products) can increase your risk of bleeding if you take them with Pristiq, especially:

• a blood thinner such as warfarin, or other medicine used to prevents blood clots; or

• an NSAID (nonsteroidal anti-inflammatory drug) - aspirin, ibuprofen (Advil, Motrin), naproxen (Aleve), celecoxib, diclofenac, indomethacin, meloxicam, and others.

This list is not complete and many other drugs may affect Pristiq. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.