Ketamine And Effexor XR Interaction

In our latest question and answer, the pharmacist discusses the potential interaction between ketamine and Effexor XR.


What would happen if I took ketamine within 5-8 hours of my Effexor XR dose?

Asked by John On Jun 09, 2019

Answered by
Medical Content Reviewed By PharmacistAnswers Staff

On Jun 10, 2019
Blue Capsules With Text - Effexor With Ketamine


There is a potential drug interaction between ketamine and Effexor XR, but it is thought to be relatively minor.

Our own interaction checker states the following regarding the combination:

The risk or severity of adverse effects can be increased when Ketamine is combined with Venlafaxine [Effexor].

PharmacistAnswers Interactions

I'll go into more detail in the next section, but basically, the use of both can cause additive side effects, such as sedation, dizziness, and drowsiness.

However, seeing how ketamine is used as an anesthetic and has a relatively short duration of action, the interaction with Effexor isn't much of a concern for most individuals.

What Is Ketamine?

Ketamine is a sedative-hypnotic drug that is used to provide anesthesia for medical procedures. However, it is also a well-known drug of abuse as it has effects similar to PCP (phencyclidine).[1]

It has a rather complex mechanism of action but mainly works by blocking N-methyl-D-aspartate (NMDA) receptors, which produces pronounced analgesia, anesthetic, and dissociative effects.[2]

Ketamine is only available in injectable forms for medical use but can be found in oral dosage forms in illicit products.

It recently has been investigated for the treatment of 'treatment-resistant depression' and has shown promise, but further studies are needed.

What Is Effexor XR?

Effexor XR (venlafaxine) is classified as an SNRI (serotonin-norepinephrine) antidepressant.

In addition to its use for the treatment of depressive disorders, it also can be used to treat (among other things):[3]

  • Anxiety
  • Migraines
  • Fibromyalgia
  • Eating disorders

Effexor XR, like all antidepressants, is associated with several well-known side effects including:

  • Sedation
  • Insomnia
  • Stomach upset
  • Diarrhea
  • Dizziness
  • Vomiting
  • Weight gain (or loss)

These side effects tend to be most pronounced when first starting therapy, and generally resolve the longer you take the drug.

The Interaction

Taking ketamine with Effexor XR could cause additive side effects, including more pronounced:

  • Sedation
  • Dizziness
  • Confusion

Again though, this interaction isn't of much concern since ketamine (when used as medically indicated) is used for anesthesia purposes.

There are no known cases of more severe side effects occurring with the use of both.

Additionally, ketamine doesn't last very long after it is administered. When used parentally (i.e. injected), it has a duration of action between 10-30 minutes (however, there generally is a few hour 'recovery' time). When used orally, it lasts no more than a couple of hours.[4]

So, overall, while there is an interaction between ketamine and Effexor, it generally isn't overly clinically significant.


The use of ketamine and Effexor XR (venlafaxine) together can result in additive side effects (e.g. dizziness and sedation). However, since ketamine is used for its anaesthetic effects and has a very short duration of action, the interaction isn't considered clinically significant in most cases.

  1. ^ Ketamine Monograph. PubMed
  2. ^ [Mechanisms of action of ketamine]. PubMed
  3. ^ Venlafaxine. A review of its pharmacology and therapeutic potential in depression. PubMed
  4. ^ Ketamine use in current clinical practice. PubMed

About the Pharmacist

Dr. Brian Staiger Pharm.D

Dr. Brian Staiger is a licensed pharmacist in New York State and the founder of He graduated from the University At Buffalo with a Doctor of Pharmacy degree in 2010. He has been featured in numerous publications including the Huffington Post as well as a variety of health and pharmacy-related blogs. Please feel free to reach out to him directly if you have any inquiries or want to connect! He's answered thousands of medication and pharmacy-related questions and he's ready to answer yours! Office: 716-389-3076

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