Does Pristiq Cause Tachycardia? (+5 factors)

In this article, we will discuss whether Pristiq causes tachycardia. We will also share what research suggests, possible mechanisms through which Pristiq can cause tachycardia, and other factors increasing the risk of tachycardia while taking Pristiq. 

Does Pristiq cause tachycardia? 

Yes, Pristiq may cause tachycardia in some individuals. Although tachycardia is not a commonly reported side effect of Pristiq, it may occur in rare cases, especially at higher doses. Pristiq is the brand name for desvenlafaxine which is an antidepressant.

Pristiq belongs to the class of serotonin-norepinephrine reuptake inhibitor (SNRI). It produces its therapeutic effects by blocking the reuptake of serotonin and norepinephrine (NE) thereby elevating their concentration in the brain. 

Pristiq is used to treat major depressive disorder (MDD) in adults. Although rare, it can cause tachycardia in some individuals. If you experience an elevated heart rate while taking Pristiq, you must communicate it with your healthcare provider. 

Tachycardia is a condition in which the heart rate is increased and is higher than normal. Thus, the heart beats faster than normal even when the individual is at rest, and is not exercising or anxious (1). 

When at rest, a healthy heart beats about 60-100 times per minute. In tachycardia, the heart rate is more than 100 beats per minute indicating the need for medical evaluation. Tachycardia can occur as a side effect of several medications (1). 

Persistent tachycardia puts strain on your heart which weakens your heart muscles and can lead to heart failure over time. A rapid heart rate makes it difficult for the heart to pump blood effectively which may cause dizziness, fatigue, and fainting. 

How can Pristiq cause tachycardia? 

Pristiq elevates the concentration of serotonin and NE and these neurotransmitters stimulate the sympathetic nervous system. Increased sympathetic activity in the heart causes it to beat faster and also increases the blood pressure (2). 

Thus the effect of neurotransmitters on cardiac activity is the mechanism through which Pristiq may result in tachycardia. It is however a rare side effect and does not occur in every individual taking Pristiq. 

What does research suggest?

Tachycardia caused by Pristiq is not a widely reported side effect however, it is observed in higher doses of Pristiq. Different clinical trials have been conducted to study the effects of different doses of Pristiq in the management of MDD (3). 

Results from these trials indicate that tachycardia is not usually reported in individuals taking a dose of 50mg/day. The occurrence of tachycardia is associated with higher doses of Prisitq including 100 mg, 200 mg, and 400 mg per day (3). 

Research also indicates that tachycardia is a common symptom of Pristiq overdose. A study assessed 182 cases of Pristiq overdose incidents and concluded that the overdose causes minor effects including tachycardia and mild hypertension (4). 

Literature suggests that common symptoms of Pristiq overdose include tachycardia along with seizures, dilated pupils, vomiting, and changes in the levels of consciousness (5). 

The research mentions that Pristiq can cause serotonin syndrome as it increases the level of serotonin in the body. This condition is serious however, it is rare to occur. One common symptom of serotonin syndrome is tachycardia (6). 

What factors increase the risk of tachycardia while taking Pristiq?

Different factors increase the risk of tachycardia if present in an individual who is taking Pristiq. They are as follows: 

High doses of Prsitiq: 

The intensity of the side effects of Pristiq depends on its dose. Higher doses are associated with heightened side effects (7). Thus, an individual taking Pristiq at a dose higher than 50mg/day may experience tachycardia as a side effect.

Concomitant use of other medications: 

Other medications that also affect the levels of serotonin in the body increase the risk of serotonin syndrome and tachycardia. Thus, Pristiq should not be taken with these medications. They include (6):

• monoamine oxidase inhibitors
• tricyclic antidepressants
• triptans
• OTC drugs like St. Johns Wart

Pre-existing heart conditions:

Individuals suffering from heart conditions are at higher risk of developing tachycardia while taking Pristiq. These conditions include pre-existing arrhythmias, coronary artery disease, cardiomyopathy, and myocarditis (1).  

Electrolyte imbalance: 

Electrolyte imbalance increases the risk of tachycardia while taking Pristiq. It may include hyperkalemia (increased serum potassium), hypomagnesemia (decreased serum magnesium), and hypocalcemia (decreased serum calcium) (1). 

Other health conditions: 

Health concerns other than heart-related conditions also increase the risk of tachycardia while taking Pristiq. These conditions include: 

• pulmonary emboli
• hypoxia
• hypoglycemia
• dehydration
• anemia 

What to do if Pristiq causes tachycardia?

If you experience tachycardia or increased heart rate while taking Pristiq, you should communicate it with your healthcare provider. Your healthcare provider will assess you to find out the possible causes of your increased heart rate. 

If tachycardia is solely caused by Pristiq, your healthcare provider may reduce your dose and monitor your response. Do not consider changing the dose without medical guidance and don’t cut the tablet in half for dose reduction.

Pristiq is generally considered safe and well-tolerated at the dose of 50mg/day and side effects are heightened in higher doses. If dose reduction doesn’t help, your doctor may switch to a different medication. 

If you experience tachycardia while taking Pristiq, do not discontinue the medication abruptly. Abruptly stopping Pristiq at higher doses is associated with discontinuation syndrome which may cause dizziness, anxiety, sweating, seizures, and confusion. 

Your healthcare provider may also recommend lifestyle changes to reduce the risk of tachycardia while taking Pristiq. This may include limiting caffeine intake, stress management, maintaining adequate hydration, and following a heart-healthy diet. 

What are some other side effects of Pristiq?

Tachycardia is a rarely reported side effect of Pristiq. Some commonly reported side effects of Pristiq include (6):

• abdominal pain
• reduced appetite
• constipation
• nausea
• headache
• dizziness
• sweating

In my opinion, Pristiq rarely causes tachycardia when prescribed in therapeutic doses. This side effect is more likely to occur if you are taking higher doses of Pristiq. Tachycardia has been reported as a common symptom in cases of Pristiq overdose. Pristiq increases the level of neurotransmitters which increase cardiac sympathetic activity and elevate the heart rate. Factors like higher doses, concomitant use of some medications, and some health conditions increase the risk of tachycardia while taking Pristiq. You must communicate with your healthcare provider if you experience tachycardia while taking Pristiq. 

References