Generic Phentermine May Be Safe and Effective for Longer-Term Treatment

A study revealed that generic phentermine, a popular weight loss drug, may be safe and effective for longer-term treatment. Researchers at Wake Forest Baptist Health and the PORTAL Network analyzed data from the electronic health records of over thirteen thousand adults who were prescribed generic phentermine for short-term use versus longer-term use of a year or more.

The study found that people who stayed on generic phentermine longer experienced greater weight loss than those who took the drug for three months or less. Also, individuals who took the drug short term and then quit were more likely to regain the weight they had lost when compared with people who stayed on generic phentermine.

More importantly, individuals who used phentermine for a year or more had no apparent increase in blood pressure, risk of heart attack, stroke or death for as long as three years afterwards ( 1 ).

According to Kristina H. Lewis, M.D., assistant professor of epidemiology and prevention at Wake Forest Baptist, if you struggle to lose weight through diet and exercise alone:
“(…) medications or surgery can help. Generic phentermine is an effective and affordable option, but now that we view obesity as a chronic disease, it’s important to have medications that can be used indefinitely. Most new weight-loss drugs are approved for long-term use, but unfortunately the newer drugs can be expensive if they are not covered by insurance.”

It’s important to note that this study did not look at individuals with potential contraindications, including a history of stroke, heart disease, or high blood pressure. Everyone, regardless of health history, must take weight loss drugs with caution and medical supervision.

What Is Generic Phentermine?

Phentermine is the most popular weight loss medication in the United States. Its active ingredient, phentermine hydrochloride, is an amphetamine-like substance that suppresses appetite and boosts energy. Phentermine 37.5 mg is the most commonly-prescribed dose in the market.

Phentermine 37.5 mg is available as a brand-name or generic drug. Most patients gravitate towards the affordability of generic phentermine, but some prefer a branded version of the weight loss drug (such as Adipex-P, Qsymia, Lomaira). 82% of phentermine prescribed in the US is generic ( 2 ).

How Long Is It Safe to Take Phentermine?

The study demonstrated that phentermine usage of ‘a year or more’ may be safe and effective. This time span was associated with increased weight loss ( 3 ).

However, currently the FDA recommends using phentermine for only three months at a time. Talk to your doctor about the best approach for you.

What are the Long-Term Side Effects of Taking Phentermine?

The research indicated that individuals who used phentermine for a year or more had no apparent increase in blood pressure, risk of heart attack, stroke or death for as long as three years afterwards.

Phentermine users should however be aware that further studies have to be undertaken to confirm the effects of taking phentermine long-term.

Also, besides possible long-term side effects, phentermine can come with a number of short-term side effects such as headache, dry mouth, constipation, fatigue, and insomnia, among others.

  1. Lewis KH, Fischer H, Ard J, Barton L, Bessesen DH, Daley MF, Desai J, Fitzpatrick SL, Horberg M, Koebnick C, Oshiro C, Yamamoto A, Young DR, Arterburn DE. Safety and Effectiveness of Longer-Term Phentermine Use: Clinical Outcomes from an Electronic Health Record Cohort. Obesity (Silver Spring). 2019 Apr;27(4):591-602. doi: 10.1002/oby.22430. PMID: 30900410.
  2. CVS. (2019). CVS Pharmacy.
  3. Science Daily. (2019). Generic weight-loss drug may be safe and effective for long-term treatment.