For those suffering from major depressive disorder (MDD), taking antidepressants can be a significant step in allowing them to improve their mental health.

One common prescription medication often used to treat MDD is venlafaxine (often known by the brand name Effexor). On this page, we outline some important information about this medication.

What is venlafaxine (Effexor)?

What is venlafaxine? How does it work?

Venlafaxine is an antidepressant approved to treat conditions such as MDD, generalized anxiety disorder (GAD), social anxiety disorder, and panic disorder. It may sometimes be used off-label to treat hot flashes in women who are experiencing menopause or are taking breast cancer medication.

Venlafaxine belongs to a class of medications called serotonin-norepinephrine reuptake inhibitors (SNRIs). SNRIs like venlafaxine help increase the levels of the neurotransmitters serotonin and norepinephrine in the brain. Both serotonin and norepinephrine affect mood and sense of wellbeing. Increased levels of these neurotransmitters can help improve how we feel. 

How is venlafaxine typically used?

Venlafaxine is usually prescribed in its extended-release formulation known as venlafaxine ER or Effexor XR. A common starting dose of venlafaxine ER for adults is 37.5-75 mg orally, once daily. This can be taken in the morning or evening. However, it is important to be consistent with your timing. Moreover, your prescription might differ depending on your medical history and what you are being treated for. 

Often, doctors will start their patients off on a lower dose and gradually increase the dosage over time until reaching an appropriate daily dosage. This helps avoid any negative reactions. As a result, it might take time to begin seeing the full benefits of venlafaxine, but it is still important to consistently take your medication and follow your doctor’s recommendations. 

If you happen to miss a dose of venlafaxine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular schedule. Do not double dose.

Do not stop taking venlafaxine without talking to your doctor, as this may cause a negative reaction. If your doctor feels that you are ready to stop taking venlafaxine, they will gradually reduce your dose over several weeks until it is safe to stop taking the medication altogether.   

What are some possible side effects?

Some common side effects of venlafaxine include:

• Drowsiness
• Headaches
• Vomiting
• Diarrhea
• Nausea

Some serious (but uncommon) side effects include:

• Difficulty breathing or swallowing
• Chest pain
• Seizures
• Fever
• Hallucinations

Call 911 or seek emergency care if you notice any severe side effects. You can see a more comprehensive list of venlafaxine side effects here. 

Why do these side effects occur? 

Any medication can potentially lead to side effects, and a person’s likelihood of having side effects depends on many factors, including age, lifestyle, and the type of medication itself. Side effects may occur because drugs often have broad or poorly targeted effects, or the drug target itself may have many downstream effects on the body. For example, though venlafaxine works on serotonin and norepinephrine to help improve mood, there are other areas affected by these neurotransmitters, such as sleeping. Unusual changes in serotonin and norepinephrine levels can lead to side effects in other areas impacted by the neurotransmitters. 

Many non-serious side effects of mental health medications like venlafaxine go away after a few weeks as your body gets used to the medication. However, if a side effect persists, is intolerable, or severely hinders your ability to go about your daily life, talk to your doctor, because this might be a sign that the medication is not a good fit. 

How do your genes relate to venlafaxine? 

Genetics can affect your body’s response to medication. They contain instructions to create enzymes that break down medications. Venlafaxine is broken down in the body by the CYP2D6 enzyme. Some people with a certain variation of the gene for CYP2D6 might be slow metabolizers for venlafaxine. Being a slow metabolizer means your body will break down the medication more slowly than others, which means the drug sticks around in your body for longer than average and may lead to side effects. For slow metabolizers, a doctor might opt to prescribe a different medication or prescribe a lower dosage. 

One way to predict whether you’ll have a positive outcome while taking sertraline is by taking a genetic test to determine what genetic variations you have and how they affect medication metabolization. Your DNA can help your doctor rule out less suitable medications and make more informed decisions so that you can get better, faster.

Special Precautions

• Venlafaxine can make you feel lightheaded or drowsy. Avoid driving or handling heavy machinery when taking venlafaxine. 
• Inform your doctor if you or any member of your family have a history of bleeding problems as venlafaxine can cause complications. Inform your doctor if you need to take aspirin or any other medication that can increase bleeding.
• Inform your doctor if you are having any trouble concentrating or experiencing any other behavioral problems. 
• The medication can cause some people to feel irritable, agitated, or show other unusual behaviors. Some people may also get suicidal thoughts when taking venlafaxine. You should notify your doctor if you notice these. 
• Inform your doctor if you or any member of your family have any history of any mental conditions before you start taking venlafaxine. 

If you show signs of an allergic reaction to venlafaxine (hives, difficulty breathing, rash, swelling), call 911 or go to the nearest emergency department.

Some medications, vitamins, and herbs may interfere with how venlafaxine works. Make sure to tell your doctor about all other medications you are taking before starting Venlafaxine to avoid negative interactions. For full details, see the FDA’s full list of precautions. 

Looking to find the right medication for your mental health? Join Prairie today to connect to expert providers and affordable medication options.