The National Health Service is issuing important guidance for the many people across the UK prescribed the antidepressant venlafaxine. Patients are being advised to remain vigilant for a specific set of potentially serious side effects that require immediate contact with a doctor or the NHS 111 service.
Understanding Venlafaxine and Its Common Effects
Venlafaxine is a widely used medication known as a serotonin and noradrenaline reuptake inhibitor (SNRI). It is primarily prescribed to treat major depression, but is also used for anxiety disorders and panic attacks. The drug works by increasing the levels of two key neurotransmitters, serotonin and noradrenaline, in the brain, which helps to improve and stabilise mood.
It is typically taken as a daily tablet or capsule. While the NHS states that it has fewer side effects than older antidepressants, it is not without them. Most people begin to feel some improvement after one or two weeks, but it can take four to six weeks for the full benefits to be felt.
Common, usually mild, side effects include headaches, nausea, dry mouth, and increased sweating. These often subside on their own after the first couple of weeks as the body adjusts to the medication.
Serious Side Effects: When to Seek Immediate Help
While uncommon, affecting fewer than 1 in 100 people, some side effects of venlafaxine are considered serious and warrant prompt medical attention. The NHS stresses that if you experience any of the following symptoms, you should call your GP or 111 without delay.
You must contact a doctor or 111 if you experience:
- The whites of your eyes or your skin turning yellow (a sign of possible liver issues).
- Unexplained bleeding, such as from the gums, coughing up blood, blood in urine, or easy, excessive bruising.
- Signs of stomach bleeding, including black or red stools, or vomiting blood.
- Severe dizziness, shortness of breath, or a fast, pounding, or irregular heartbeat.
- Unexplained muscle pain, weakness, or frequent cramps.
- Constant headaches, long-lasting confusion, or weakness.
- Any changes in eyesight, such as blurred vision or dilated pupils.
- Feelings of extreme euphoria, excessive excitement, or severe restlessness.
- Any thoughts about harming yourself or ending your life.
Additionally, you should book a routine appointment with your GP if you notice significant, unintentional weight loss or gain, or experience major changes to your menstrual cycle, such as very heavy bleeding, spotting, or bleeding between periods.
Long-Term Use and Final Advice
The NHS guidance is clear that for most people, taking venlafaxine over a long period is considered safe and is not associated with lasting harmful effects. The benefits for treating depression and anxiety generally outweigh the risks of these uncommon side effects.
However, patient awareness is crucial. Never stop taking your medication suddenly due to concerns, as this can cause withdrawal symptoms. If you have any worries about side effects or your treatment plan, your first port of call should be a discussion with a qualified pharmacist, your GP, or another prescribing healthcare professional. Full official guidance on venlafaxine can always be found on the NHS website.
