Pristiq (Desvenlafaxine) for Anxiety and Panic Disorder

Antidepressant medications are frequently prescribed to help manage the symptoms of anxiety and panic disorder. One such option is Pristiq. Learn how Pristiq can help these conditions, along with its potential side effects, the timeline for working, dosage amount, precautions, and the capacity for withdrawal.

What Is Pristiq?

Pristiq (desvenlafaxine) belongs to a class of antidepressants called serotonin and norepinephrine reuptake inhibitors (SNRIs). These medications reduce the absorption of serotonin and norepinephrine in the brain and were first used to treat mood disorders, such as major depressive disorder (MDD).

SNRIs were later found to be an effective treatment for a variety of mental health conditions. Today, in addition to being used to help treat MDD, they are also prescribed for anxiety disorders, panic disorder, and social phobia.

Pristiq for Anxiety and Panic Disorder

The U.S. Food and Drug Administration (FDA) has approved Pristiq for the treatment of MDD. However, it also has a few off-label uses, of which anxiety and panic disorder are two.

Anxiety

Nearly one in five people in the U.S. have an anxiety disorder, making this the most common mental health disorder nationwide. Anti-anxiety medications (anxiolytics) are one pharmacological treatment option. But research has found that desvenlafaxine—known by the brand name Pristiq—provides benefits as well.

For example, in a 12-week double-blind study, desvenlafaxine was found effective for easing generalized social anxiety disorder. In this case, the group receiving the drug had a 9.7-point greater reduction in their anxiety scores than those receiving a placebo.

A 2019 study compared the effects of desvenlafaxine with escitalopram, a generic drug with the trademark name Lexapro, for postmenopausal women with anxiety and depression. While escitalopram was more effective for treating depressive symptoms, the drugs were equally able to reduce anxiety.

Panic Disorder

Naturally occurring chemicals in the brain, known as neurotransmitters, are responsible for various bodily functions. These chemical messengers are believed to be imbalanced for those with mental health conditions.

Antidepressants work to restabilize certain neurotransmitters. Pristiq, specifically, impacts the neurotransmitters serotonin and norepinephrine, both of which are thought to be dysregulated in people with panic disorder.

Serotonin influences many functions, including mood and sleep regulation. Norepinephrine is connected to the fight-or-flight response, which is the way we react to stress and anxiety. Pristiq can help bring equilibrium to both, leading to reduced anxiety, less severe panic attacks, and enhanced mood.

Potential Side Effects of Pristiq

As with any prescribed medication, there are potential side effects of taking Pristiq.

Common Side Effects

Some of Pristiq's most common side effects include:

• Constipation
• Decreased appetite
• Diarrhea
• Dry mouth
• Fatigue
• Headache
• Increased sweating
• Insomnia
• Nausea
• Nervousness
• Restlessness
• Tremors
• Vomiting

You may experience some, all, or none of these effects. If you do, they typically diminish or become more manageable within a week or two of starting this medication. If they persist or worsen, consult your healthcare provider.

Serious Side Effects

Other Pristiq side effects can be more serious, making it important to contact your healthcare provider or seek emergency medical attention if any of these occur. Some of the rare but also more serious side effects of Pristiq include:

• Angle-closure glaucoma
• Changes in taste
• Heart attack
• Increased heart rate or severely elevated blood pressure
• Increased salivation
• Increased urination frequency or trouble urinating
• Irregular menstrual cycle
• Low blood pressure
• Low sodium
• Rash
• Serotonin syndrome
• Teeth grinding

How Long It Takes Pristiq to Work

You probably won't notice an immediate improvement in your anxiety or panic disorder when taking Pristiq. This is because it takes approximately four to five days to reach a steady state of this drug in the blood.

After one to two weeks, you may notice that you are sleeping better, have more energy, or that your appetite is improved. Mood-related effects generally take a bit longer, or up to eight weeks to improve fully.

Pristiq Dosage Information

Pristiq is delivered via extended-release tablets that come in one of three doses:

• 25 mg: A square tan tablet with "W 25" imprinted on it
• 50 mg: A square light pink tablet with "W 50" imprinted on it
• 100 mg: A square orange tablet with "W 100" imprinted on it

The recommended dosage is 50 mg, taken once daily; although, more may be needed to provide the desired effect. The 25 mg tablets are generally used to reduce the drug slowly when discontinuing treatment.

If you are prescribed Pristiq for anxiety or panic disorder, the tablets should be taken whole (don't crush or cut them), and you can take them with or without food.

Pristiq Overdose

Pristiq overdose is rare but can occur if this drug is taken in high amounts. One study found 182 cases of desvenlafaxine overdose over a six-year period, 75 of which involved taking this medication only and 107 involving the use of this drug and at least one other.

Symptoms associated with Pristiq overdose included mild hypertension (high blood pressure) and tachycardia (heart rate over 100 beats per minute). None of the overdoses studied required intensive care treatment or resulted in death, and the risk of having seizures or developing serotonin toxicity was low.

Precautions for Pristiq

Some of the precautions to be aware of when taking Pristiq for anxiety or panic disorder include:

• Black box warning: In 2007, Pristiq and other antidepressants were given what's called a “black box warning.” This label was prompted by the FDA after it was determined that these medications could potentially increase the user’s risk of suicidal thoughts and behaviors. Adolescents and young adults can be especially impacted by this possible side effect. Any young person taking Pristiq must be closely monitored for mood alterations and suicidal thoughts.

• Alcohol consumption: Drinking alcohol is not recommended while taking Pristiq as doing so may increase the toxicity of this medication. Mixing alcohol with Pristiq can also lead to the drug being ineffective.
• Pregnancy/nursing: It's possible to pass Pristiq to a child during pregnancy or through breast milk. If you're pregnant or nursing, consult your practitioner about the possible risks of taking Pristiq.
• Children and teens: Studies have found that 25 mg to 50 mg of desvenlafaxine per day is generally considered safe for pediatric patients. However, the FDA does say that safety has not been established for this demographic, so the potential risks must be balanced with clinical need. The child's healthcare provider can help decide if Pristiq should be used.
• Older adults: The cardiovascular side effects of Pristiq can be more intense for older adults. Monitoring and, if needed, reducing the dosage amount can help reduce these potential effects.

Interactions

Pristiq can interact with certain medications, potentially increasing or decreasing the drug's response. Drugs that can negatively interact with Pristiq include:

• Antiplatelet or anticoagulant drugs
• Monoamine oxidase inhibitors (MAOIs)
• Other serotonergic drugs

Withdrawal From Pristiq

When discontinuing Pristiq, your healthcare provider will likely reduce your dosage slowly to help reduce any unwanted effects. If Pristiq is stopped abruptly, withdrawal may occur, creating symptoms such as:

• Abnormal dreams
• Anxiety
• Diarrhea
• Dizziness
• Fatigue
• Headache
• Hyperhidrosis (excessive sweating)
• Insomnia
• Irritability
• Nausea

These withdrawal symptoms can also occur in people who have been taking Pristiq for a long period of time.