Venlafaxine (Effexor XR) was introduced as an antidepressant, although it is sometimes used to treat other mental conditions such as panic disorder. Venlafaxine is classified as an SNRI-a serotonin-norepinephrine reuptake inhibitor. That puts it in the same category as duloxetine (Cymbalta) and desvenlafaxine (Pristiq). These medications affect many systems of chemical messengers (the neurotransmitters serotonin, norepinephrine and dopamine) in the brain.

Side Effects and Interactions

The side effects of venlafaxine include nausea, headache, anxiety or agitation, insomnia, drowsiness, excessive sweating and loss of appetite. Appetite problems may result in weight loss, but venlafaxine is by no means a weight-loss drug.

Dry mouth, dizziness, constipation, tremor and blurred vision are other possible side effects. Venlafaxine may lead to increased blood pressure in some people, so blood pressure should be monitored on a regular basis. Blood cholesterol levels may also rise while a person is taking venlafaxine. Excessive sweating or yawning, exhaustion, rapid heartbeat and abnormal dreams are among the common reactions, as are sexual difficulties such as erectile dysfunction and ejaculatory problems.

Serious Reactions of Venlafaxine

Venlafaxine carries a black box warning to alert prescribers, patients and their families that those taking the drug may be at increased risk for committing suicide. This risk is strongest for young people 24 years old or less. The drug is not approved for use in children.

As with other antidepressants, people taking venlafaxine may find their depression worsening or experience manic symptoms.

Some patients on venlafaxine have experienced seizures. Report any symptoms or suspected side effects without delay.

Pancreatitis, liver damage and severe skin reactions that may require hospitalization are among the rare but serious problems that may be triggered by venlafaxine. Hyponatremia (a dangerously low sodium level), heart rhythm disturbances and excessive bleeding have also been reported.


Stopping venlafaxine suddenly can result in symptoms such as nausea, diarrhea, digestive distress and visual disturbances. Dizziness and vertigo may be accompanied by a feeling variously described as “head in a blender” or “brain sloshing.” Many people who stop venlafaxine suddenly also complain of “brain zaps”-sensations like electric shocks to the head. Headaches, anxiety, tremors and nerve tingling or other strange sensations can be very unsettling. Anxiety and irritability are common withdrawal reactions, as are extreme fatigue. This discontinuation syndrome can be disabling. Sudden withdrawal should be avoided if at all possible; unfortunately, doctors do not have adequate instructions on how slowly people may need to decrease the dose of this medication.


Because of the possibility of a life-threatening interaction called serotonin syndrome, venlafaxine must not be taken by anyone on an MAO inhibitor such as isocarboxazid, phenelzine, procarbazine, selegiline or tranylcypromine. Other drugs that inhibit monoamine oxidase and must be avoided include the antibiotic linezolid (Zyvox) and methylene blue injections.

A person who has been taking an MAO inhibitor should wait at least 14 days after stopping it before beginning to take venlafaxine; after stopping venlafaxine, a person should wait 7 days before starting on an MAO inhibitor.

Certain medications, particularly amiodarone (Cordarone), dronedarone (Multaq) and thioridazine can increase the possibility of QT prolongation, a potentially deadly change in heart rhythm, and should not be taken in combination with venlafaxine.

Other Drugs That React Badly with Venlafaxine

antidepressants such as citalopram (Celexa),

antipsychotic drugs such as asenapine (Saphris),

cancer treatments such as crizotinib (Xalkori),

migraine headache medicines such as almotriptan (Axert), eletriptan (Relpax), frovatriptan (Frova), naratriptan (Amerge), sumatriptan (Imitrex) and zolmitriptan (Zomig)

hepatitis C medications such as boceprevir (Victrelis),

HIV drugs such as cobicistat (Stribild)

quinine derivatives such as chloroquine,

special-use antibiotics such bedaquiline (Sirturo),

et can slow removal of Effexor from the body, and a person who must take both may need a dosage adjustment. This is most likely to affect individuals with high blood pressure or liver problems, and the elderly.

Certain other medications, such as quinidine, may increase blood levels of Effexor, but there is limited data on interactions, and there may be other drug interactions that have not yet been identified.

Ask your doctor and pharmacist to check whether any other drug or herb you take is safe in combination with Effexor.

Special Precautions

Venlafaxine can cause or exacerbate narrow-angle or angle-closure glaucoma and should not be given to anyone with this eye condition.

Some depressed people experience anxiety and insomnia as part of the symptoms of their condition. Effexor may exacerbate these problems in some patients.

The drug may also worsen the manic phase for some manic-depressive individuals and not be appropriate for continued treatment.

Any medicine affecting the brain may have the potential to slow reflexes or impair judgment. Such problems did not appear significant in clinical trials, but patients are best advised not to drive or use hazardous machinery until they can determine (preferably through an objective assessment) that they are not adversely affected by Effexor.

As of this writing, Effexor is a new drug with relatively little data available. Studies have not established that it is effective for long-term use of more than six weeks. It is advisable for doctor and patient to reevaluate this therapy periodically to make sure that it continues to be appropriate.

Taking the Medicine

Effexor should be taken with food. The dosage should be individually adjusted and will determine whether Effexor is taken two or three times daily. When going off Effexor, a person should ask the doctor for guidelines on gradual withdrawal.

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  1. DMC5

    I’m amazed, I have to admit. Seldom do I encounter a blog that’s both equally educative and entertaining, and without a doubt, you’ve hit the nail on the head. The issue is an issue that too few men and women are speaking intelligently about. I am very happy I found this during my hunt for something concerning this.

  2. anais lorie

    I’ve been taking 150mg Venlafaxine for approx. 4 months now and have lost my appetite. I eat when I get very hungry or to complete my daily calorie intake. But I have lost some weight and only weigh 110 pounds (7.8 stones) so can’t afford to lose more.
    Does anyone know a way to counter the loss of appetite?

  3. Renee

    I was on this medication for a couple of years and despite the initial support it gave me, over time I felt like it was making me crazy. I talked to my doctor about getting off of it, so I went from the 75mg slow release to 37.5mg slow release and there were no side effects. However, when I tried to go to 12.5mg dose after a month, I was generally “mushy brained”, had zaps all over my body- not just brain zaps, and I felt disoriented.

    I rode it out though, and after a couple of months tried to taper off by taking the lower dose every other day- this did not work. I was unable to function, so I talked to my doctor and she said there wasn’t a lower dose. Fast forward 6 more months, and I spoke with a pharmacist who said there was indeed a lower dose, and a non-time released 12.5mg (so I could cut them in half).

    I was only able to get a prescription for the non-time release ones, so I took half of those for two weeks, then a quarter for another two weeks. During the time I took the quarter of the 12.5MG, I was getting headaches, disorientation, and zaps, but everything was tolerable. I finally stopped on 12/31 and am still having the zaps (like a mild electric shock) all over my body.

    I am thrilled to be off of this stuff! I am not a doctor of any kind, but would not recommend this medication to anyone based on my experience.

  4. Jen

    I’ve been taking 150mg XR Effexor for almost 6 years now. I will say it has helped my depression and anxiety. Yes, the withdrawals are unbelievable. I seriously couldn’t function. I was one dose short, while waiting for the mail order. Couldn’t walk, drive, barely talk…just crying all day. The brain zaps though are something I never want to experience again. I hate depending on this drug, although it has helped me a lot. If you are considering taking this, do a little bit of research. What might work well for someone, might not work well for you. Good luck to everyone ?

  5. Daniele

    I got a prescription for Venlafaxine 37,5mg and came here to find out what others have to say about this before starting. Comments are mixed and I am not sure if I should even start now.

  6. Robert
    Dallas, TX

    I started venlafaxine a few years ago while going through a difficult time. I lost my job, my wife was diagnosed with cancer, and my son got himself sent to prison. I was feeling very down and my doctor put me on 75 mg of venlafaxine daily. I don’t know if it was the pills or just time, but I started feeling better.

    After taking this stuff for a couple of years I asked my doctor about stopping and she said everything is going well with you so you should continue. Two more years had passed and I had put on about 50 pounds (3.6 stone or 22.6 kg) so I insisted that we start a cessation program. She first had me dump about a fourth of the 75 mg capsules and take this 25% reduced level for 10 days. Then I received a 30 day supply of 37.5 mg venlafaxine capsules and started taking them for 10 days. Here is where I started feeling a little dizzy, with ringing in my ears, and “brain zaps”. I then reduced the 37.5 mg capsules by 25% for 10 days, followed by 50% reduction for 10 days and then 75% reduction for the balance of the capsules.

    A couple of days after each reduction in strength were very challenging. There were head zaps, body aches, disorientation and generally feeling miserable. I did some research and found information about some people using Prozac 10 mg to reduce the withdrawal symptoms. Figuring I had nothing to lose, I ask my doc for a 30 prescription for generic Prozac 10 mg and took one. After a few hours the symptoms diminished but I became worried that getting off this might be difficult too. Without any real medical direction, I took a Prozac every other day for a week, and then once every two days and finally stopped.

    I still have ringing in my ears and mild brain zaps but I can live with them. I’m hoping that with time these will go away. I think these drugs did scary stuff to my body chemistry and I suggest finding alternatives whenever possible.

    • victoria
      Lexington, KY (40502)

      RUN!!!! Run from this drug. My vision has gotten worse over two years as I was on 150 mg., then 75 mg.,
      I stoped on my on, going through menopause, in a suboxzone clinic and only have Buspar to take. My doctor didn’t warn me that because I already have astigmatism in one eye that taking Effexer could cause blindness. My vision is getting worse.

      This has been the worst, most depressing week of my life–health-wise. I walked in front of a car, yesterday. My reactions to any normal situation have slowed and are almost gone or disappeared.

  7. Belle
    sydney nsw

    Hi I have been on effexor 75mg slow release for the past 12 months previously I was on lovan for approx 5 and a half years it was no longer working. Doc said try effexor after agonising over it for 3 months stupid me decided to take it, well it worked great no depression no anxiety no suicidal thoughts, but god forbid forget to take this medicine 1 day and I’m completely unable to function.

    Trying to come off after 3 days I was in a feotal position on my lounge in tears then my evil thoughts returned. My mouth goes numb I stutter cant get my words out it is like my brain is delayed compared to my body out burst of crying then anger wanting to slam my car up the back of the truck and still be able to watch it roll and burst into flames feels like I’m having electric shocks through out my whole body this drug is freaking me out to think that I will one day have to come off it as I do not want to rely on drugs for the rest of my life.

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