From the Guidelines
Venlafaxine is associated with several common side effects, including nausea, headache, dizziness, and sexual dysfunction, as well as more serious but less common side effects like serotonin syndrome and abnormal bleeding, as reported in a 2020 study 1.
Common Side Effects
- Nausea and vomiting
- Headache
- Dizziness
- Dry mouth
- Sweating
- Insomnia
- Sexual dysfunction Some patients may also experience increased blood pressure, particularly at higher doses, so regular blood pressure monitoring is recommended. Gastrointestinal issues like constipation or diarrhea may occur, especially when starting treatment.
Serious Side Effects
- Serotonin syndrome (confusion, rapid heart rate, high fever, and muscle rigidity)
- Abnormal bleeding
- Low sodium levels
- Seizures
- Sustained clinical hypertension
- Increased blood pressure and pulse
Discontinuation Symptoms
Abruptly stopping venlafaxine can lead to withdrawal symptoms, including dizziness, nausea, headache, irritability, and "brain zaps," so the medication should always be tapered gradually under medical supervision, as noted in the 2020 study 1.
Special Considerations
Venlafaxine may be associated with a greater risk of suicide than other SNRIs, and both venlafaxine and desvenlafaxine have been associated with overdose fatalities, highlighting the need for careful monitoring and medical supervision when prescribing this medication, as discussed in the 2020 study 1.
From the FDA Drug Label
Venlafaxine HCl and other antidepressant medicines may cause serious side effects, including:
- Suicidal thoughts or actions
- Serotonin Syndrome
- Changes in blood pressure
- Enlarged pupils (mydriasis)
- Anxiety and insomnia
- Changes in appetite or weight
- Manic/hypomanic episodes
- Low salt (sodium) levels in the blood
- Abnormal bleeding
- Elevated cholesterol
- Lung disease and pneumonia
- Severe allergic reactions
The possible side effects of venlafaxine include:
- Suicidal thoughts or actions
- Serotonin Syndrome
- Changes in blood pressure
- Enlarged pupils (mydriasis)
- Anxiety and insomnia
- Changes in appetite or weight
- Manic/hypomanic episodes
- Low salt (sodium) levels in the blood
- Abnormal bleeding
- Elevated cholesterol
- Lung disease and pneumonia
- Severe allergic reactions
- Unusual dreams
- Sexual problems
- Loss of appetite, constipation, diarrhea, nausea or vomiting, or dry mouth
- Feeling tired, fatigued or overly sleepy
- Change in sleep habits, problems sleeping
- Yawning
- Tremor or shaking
- Dizziness, blurred vision
- Sweating
- Feeling anxious, nervous or jittery
- Headache
- Increase in heart rate 2 2 2
From the Research
Venlafaxine Side Effects
- The most common side effects of venlafaxine include nausea, diarrhea, fatigue, somnolence, and sexual side effects 3
- At higher doses, venlafaxine can produce mild increases in blood pressure, diaphoresis, tachycardia, tremors, and anxiety 3
- Venlafaxine has a potential disadvantage of dose-dependent blood pressure elevation, most likely due to the NE reuptake inhibition caused by higher doses 3
- The risk of cardiovascular adverse effects and fatal overdoses is higher with venlafaxine compared to most SSRI antidepressants 4
- Venlafaxine increases the risk of serious adverse events, such as sexual dysfunction and anorexia, and non-serious adverse events, including nausea, dry mouth, dizziness, sweating, somnolence, constipation, nervousness, insomnia, asthenia, tremor, and decreased appetite 5
- High doses of venlafaxine (> 375 mg/day) are associated with increased frequency and severity of side effects, including fatigue, concentration difficulties, sleepiness, and weight gain 6
- The optimal dose of venlafaxine for major depression is in the lower range of its licensed dose, with an initially increasing dose-efficacy relationship up to around 75-150 mg 7
Comparison to Other Antidepressants
- Venlafaxine has a similar efficacy to SSRIs, but with a higher risk of cardiovascular adverse effects and fatal overdoses 4
- Duloxetine, another SNRI, has a more balanced profile of binding and a higher potency than venlafaxine, but also has a higher risk of side effects, including nausea, dry mouth, dizziness, constipation, insomnia, asthenia, and hypertension 3
- Milnacipran, another SNRI, has a lower risk of side effects compared to venlafaxine, but can still cause dysuria, blood pressure elevation, and pulse elevation 3
Special Considerations
- Venlafaxine should be used with caution in patients with cardiovascular disease, as it can increase blood pressure and heart rate 3, 4
- Venlafaxine should be avoided in patients who are pregnant or breastfeeding, as it can increase the risk of pre-eclampsia and eclampsia 4
- Venlafaxine should be used with caution in patients who are taking other medications that can interact with it, such as CYP2D6 inhibitors 3