Does Phentermine Work for Weight Loss? A Diet Pill Reviewed

Phenternmine 37.5 mg

What Is Phentermine?

Phentermine is a weight loss medication. It was approved by the FDA in 1959 for short-term use for people older than 16. In the 1990s, phentermine was combined with other weight loss drugs. This drug combination was called fen-phen. After reports of serious heart problems in users, the FDA pulled the two drugs utilized in the treatment from the market. These two drugs were fenfluramine and dexfenfluramine. 

Currently, phentermine goes by the brand names Adipex-P, Lomaira, and Suprenza. Phentermine shares chemical similarities with amphetamine. Therefore, Phentermine is considered a drug and requires a prescription. 

Your doctor may prescribe phentermine if you are obese. This means that your body mass index (BMI) is equal to or greater than 30. It may also be prescribed if you are overweight. This means you BMI is equal to or greater than 27. Moreover, being overweight may also mean that you have a weight-related condition. This may include high vital signs, high cholesterol or type 2 diabetes.


Phentermine is an FDA-approved drug for weight loss. Phentermine decreases the appetite by increasing neurotransmitter levels in the brain. When the levels of norepinephrine, serotonin and dopamine increase, hunger urges decrease. Neurotransmitters are your body’s chemical messengers. 

How Does It Work?

Phentermine falls under the “anorectics” category of medicines. Anorectics are appetite suppressants. Since taking phentermine suppresses your appetite, this limits your caloric intake. As such, this will result in weight loss.

Effectiveness for Weight Loss

The average weight loss with phentermine is 5% off your initial weight. Yet, in 12 weeks, it can be high as 10%. This equates to 10–20 lbs (4.5–9 kg) weight loss for a 200 lbs (90.7 kg) person. Also, in a meta-analysis of six studies, people that took the typical dose of 27.5 mg of phentermine for 13 weeks lost an average of 6.3 kg. Contrastingly, 2.8 kg was lost in placebo groups. 

Topiramate has been known to treat seizures. However, like phentermine it also has appetite-reducing properties. The combination medication of topiramate and phentermine may be sold under the name of Qsymia. Additionally, the combination of phentermine and topiramate creates the highest likelihood of someone’s shedding 5% off their initial weight.

Furthermore, research suggests that the combination of phentermine and topiramate offers the best solution. People achieved an average weight loss of 21.6 lbs (9.8 kg) after taking the medicine for a year. The weight loss translated to decreases in waist circumference, improved insulin sensitivity and blood glucose control. Moreover, it improved triglyceride and cholesterol levels.

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