Due to the active ingredient's strong potential for addiction and abuse, as well as a lack of research surrounding the weight loss pills' long-term effects, phentermine should only be taken for twelve weeks at a time . Limiting use to "a few weeks" minimizes patients' risk of dependency, tolerance and withdrawal.
Unfortunately, given the medication's strong stimulant effects, some people still experience withdrawal symptoms when they stop taking phentermine – even after a relatively short course of treatment.
These reactions vary in severity and duration depending on the person, as well as phentermine dosage and duration.
Planning how to stop phentermine is vital in achieving long-term weight loss success. It also reduces the risk of phentermine withdrawal symptoms.
As treatment comes to a close, take time to:
Phentermine is designed as an adjunct treatment to lifestyle modifications that promote weight loss. For this reason, it is critical for patients to fortify healthy eating, exercise and self-care habits .
More, developing a strong support system – whether in-person or online – makes continued weight loss and weight maintenance a more achievable reality. For some patients, it also proves beneficial to taper their dose of phentermine in the final weeks of treatment. This allows the body to more gradually adjust to a lower level of stimulant, which helps reduce the risk of phentermine withdrawal.
It is NOT recommended to stop phentermine “cold turkey,” or very suddenly . Instead, slowly reducing intake as treatment comes to an end allows the body to acclimate and reduces the risk of withdrawal.
Read more here: Stopping Phentermine
Phentermine withdrawal symptoms are similar to those associated with other stimulants.
Common reactions include fatigue, depression/mood changes, insomnia, gastrointestinal upset and trembling [3,4]. These bothersome symptoms occur as the body adjusting to a lack of stimulant, so severity varies significantly depending on a variety of individual factors.
Seek medical attention if withdrawal symptoms are severe, worsening or interfering with daily life.
Take extra care to monitor for signs of depression/low mood, which is the typically the most dangerous side effect of stimulant withdrawal – even for months after the last dose .
Read more here: Phentermine Withdrawal Symptoms
Duration of phentermine withdrawal varies between individuals. However, most patients experience acute phentermine withdrawal in the first four days after their last dose, peaking around 3-4 days.
Lingering symptoms of stimulant withdrawal, such as low mood or fatigue, can last for weeks or months after stopping phentermine .
Read more here: Phentermine Withdrawal Time
Given the role of phentermine weight loss pills as an aid to – not replacement of – behavioral weight loss strategies, it is critical that patients transition off the medication with a plan for continued healthy living. Without a strong plan in-place for weight maintenance, almost 80% of people who achieve major weight loss gain the pounds back within two years .
Research of American adults who have lost at least 30 pounds and kept it off show that certain behaviors are highly correlated with successful weight maintenance . Some of these habits are:
Seeking support from a group of positive, sympathetic people – whether in-person or online – also proves beneficial in keeping the weight off for years to come.
Read more here: Life After Phentermine
1. Weintraub M, Hasday JD, Mushlin AI, Lockwood DH. (1984). A double-blind clinical trial in weight control. Use of fenfluramine and phentermine alone and in combination. Archives of Internal Medicine, 144(6):1143-1148.
2. American College of Cardiology. (2011, November 21). Phentermine.
4. Drugs.com. (1999, April 26). Phentermine Hydrochloride Drug Information, Professional.
5. Center for Substance Abuse Treatment. (1999). Chapter 5 – Medical Aspects of Stimulant Use Disorders. In Treatment Improvement Protocol (TIP) (Ser. 33).
7. Wing, R. R., & Phelan, S. (2005). Long-term weight loss maintenance. The American Journal of Clinical Nutrition, 82(1), 222S-225S.