People taking venlafaxine are being advised to monitor for various symptoms and side effects that may necessitate contacting 111 or their GP.

Venlafaxine, a frequently prescribed SNRI (serotonin and noradrenaline reuptake inhibitor), is primarily used to manage depression, though it can also be utilised to treat anxiety and panic attacks.

It's typically dispensed as a tablet or capsule to be ingested and functions by boosting the levels of serotonin and noradrenaline in the brain, thereby improving mood.

While NHS guidance indicates that venlafaxine has fewer side effects than older antidepressants, this doesn't imply that it's devoid of any side effects.

Generally, it takes between four to six weeks for venlafaxine to take full effect, although individuals using it often start feeling better after one to two weeks.

Common side effects of venlafaxine include sweating, nausea, dry mouth, and headaches, but these are usually mild and subside after a few weeks, according to the NHS.

However, some other side effects could be deemed more serious and might warrant a call to 111 or see a GP. These severe side effects are rare, affecting less than one in 100 people taking venlafaxine.

Guidance from the NHS highlights that you should book an appointment with your doctor if you gain or lose weight without trying or experience significant changes to your periods - this can include bleeding between periods, heavy bleeding, or spotting. Otherwise, patients are urged to call their doctor or 111 if they experience the following side effects:

• The whites of your eyes or skin turn yellow
• Bleeding from the gums
• Bruises that appear without a reason or that get bigger
• You have thoughts about harming yourself or ending your life
• Unexplained muscle pain or weakness
• Shortness of breath, or a fast or irregular heartbeat
• You experience feelings of overwhelming happiness (euphoria), excessive enthusiasm or excitement, or a feeling of restlessness that means you cannot sit or stand still
• Any changes in eyesight, such as blurred vision or dilated pupils
• You cough up blood
• Have blood in your pee
• You get constant headaches, long-lasting confusion, weakness, or frequent muscle cramps
• You have black or red poo, or blood in your vomit - these can be signs of bleeding in the stomach

It's important to remember that the NHS states long-term use of venlafaxine is generally safe with no lasting effects. Nonetheless, if you have concerns about any side effects related to your medication, you should consult a qualified pharmacist, doctor, or appropriate health professional.

Further guidance on venlafaxine can be found on the NHS website here.