Side Effects of Venlafaxine: Blood Pressure, Sweating and Discontinuation

Venlafaxine (brand name Effexor) is a serotonin-norepinephrine reuptake inhibitor (SNRI) commonly prescribed for depression, generalized anxiety disorder and other mood conditions. While many users benefit from relief of symptoms, it’s important to understand the potential side effects of venlafaxine—especially changes in blood pressure, increased sweating and withdrawal symptoms when stopping the drug.

How Venlafaxine Works

Venlafaxine boosts levels of serotonin and norepinephrine in the brain, which can improve mood, concentration and energy. It typically takes 4–6 weeks to see full benefit. Doses range from 37.5 mg up to 225 mg daily, depending on the condition treated and individual response.

Common Side Effects of Venlafaxine

Most people tolerate venlafaxine well, but some side effects occur in 10% or more of users:

• Nausea or upset stomach
• Headache
• Dizziness
• Dry mouth
• Insomnia or sleepiness
• Loss of appetite
• Constipation

These often improve over days to weeks. If they persist or worsen, talk with your doctor about adjusting your dose or switching medications.

Blood Pressure Changes

One of the well-documented side effects of venlafaxine is an increase in blood pressure, especially at higher doses.

Why It Happens

• Norepinephrine boost can constrict blood vessels
• Dose-related: more common at doses ≥ 150 mg/day

What to Watch For

• A sustained rise in systolic blood pressure of 5–10 mm Hg
• Hypertension symptoms: headache, blurred vision, chest pain

Recommendations

• Check your blood pressure before starting treatment
• Monitor at 1–2 week intervals after dose increases
• If readings exceed 140/90 mm Hg, notify your doctor
• Lifestyle measures: reduce salt intake, stay active, manage stress
• In some cases, a low-dose blood pressure medication may be added

Excessive Sweating (Hyperhidrosis)

Sweating is another commonly reported side effect of venlafaxine.

How Often It Occurs

• Seen in up to 10–15% of users
• Usually begins within the first few weeks

Typical Pattern

• More pronounced at night or during exercise
• Can be mild (damp clothing) to severe (soaked sheets, drenching)

Management Tips

• Wear moisture-wicking fabrics
• Shower before bedtime; change sheets regularly
• Avoid spicy foods, caffeine and hot environments
• Use clinical-strength antiperspirants
• If sweating interferes with daily life, discuss dose reduction or switching medications

Discontinuation Syndrome

Stopping venlafaxine abruptly can trigger a “discontinuation syndrome” that may be more intense than with other antidepressants.

Common Withdrawal Symptoms

• Dizziness or “brain zaps” (electric shock sensations)
• Insomnia or vivid dreams
• Irritability, anxiety or mood swings
• Flu-like aches, nausea or sweating

Risk Factors

• Short half-life: venlafaxine leaves the body faster than many other SSRIs/SNRIs
• Higher daily doses
• Abrupt dose reduction

Safe Tapering Strategies

• Gradual dose reduction over at least 4–6 weeks
• Consider switching to an extended-release form before tapering
• Monitor closely for emerging withdrawal symptoms

When to Seek Help

• Severe dizziness that impairs daily activities
• Persistent nausea or vomiting
• Worsening mood or suicidal thoughts

Other Less Common but Serious Side Effects

While rare, be aware of:

• Serotonin syndrome (confusion, rapid heart rate, high fever) when combined with other serotonergic drugs
• Increased bleeding risk if taking blood thinners or NSAIDs
• Eye pressure increase (glaucoma risk)
• Seizures in those with seizure disorders

If you notice any alarming signs—high fever, rash, severe headache, vision changes, chest pain—seek medical attention right away.

Tips for Managing and Monitoring Side Effects

1. Keep a Symptom Diary
   Track any new or worsening symptoms, noting date, dose and severity.
2. Stay Hydrated and Eat Balanced Meals
   Proper nutrition can reduce nausea and help stabilize blood pressure.
3. Regular Check-Ins with Your Doctor
   Review side effects, mood and blood pressure at scheduled visits.
4. Lifestyle Adjustments
   Exercise, stress-reduction techniques and good sleep habits often ease side effects.
5. Use a Symptom Checker
   Consider a free, online symptom check, using the doctor approved Ubie Symptom Checker to help you decide if you should seek medical advice.

When to Talk to a Doctor

• New or worsening high blood pressure
• Severe anxiety or panic attacks
• Intense withdrawal symptoms during tapering
• Any life-threatening or serious concerns

Your healthcare provider can adjust your dose, recommend treatments for side effects, or switch you to a different antidepressant if needed. Never stop venlafaxine suddenly without medical guidance—doing so increases the risk of withdrawal symptoms.

---

This overview of the side effects of venlafaxine is based on credible sources, including prescribing information and clinical guidelines. Always speak to a doctor about any concerns or symptoms that could be serious—they can give you personalized advice and ensure your treatment is safe and effective.