Gums asked
I see that it is recommended that Phentermine be stopped one week before a surgical procedure. Does a higher daily dose of Phentermine warrant stopping sooner than one week before surgery? Also, does a patient who is about to have a surgical procedure need to taper Phentermine, or can a person just stop?
Answer
We've written a few articles on this subject that may be helpful for you:
Below are some highlights from those articles:
- Phentermine is always recommended to be discontinued before surgery, for multiple reasons. These reasons include the fact that phentermine can interfere with anesthesia and put you at risk for serious adverse events.
- In general, phentermine should be discontinued at least one week prior to surgery, with some recommendations being 2 to 3 weeks before surgery. Be sure to follow the instructions given to you by your doctor.
- Although phentermine is similar to amphetamine products, most data indicates that it does not produce significant withdrawal reactions and can often be discontinued abruptly. Per one study:
"Abrupt cessation of long-term phentermine therapy does not induce amphetamine-like withdrawal. Long-term phentermine therapy does not induce phentermine cravings. Symptoms observed after abrupt phentermine cessation represent loss of therapeutic effect and are not withdrawal."
Regardless of the dose of phentermine you are taking, discontinuation instructions are the same as drug elimination from our body is proportional to the drug concentration (for most drugs, including phentermine). This means the higher the drug concentration, the higher the elimination rate.
Around 50% of phentermine is metabolized and eliminated every 19-24 hours (this is also known as the half-life of the drug). Therefore, regardless of drug concentrations in your body, it will take approximately the same amount of time for it to be completely eliminated from the body.
