What are the side effects to Phentermine 37.5 mg? A friend just starting taking this for weight loss.

Anon,
My sister took this medicine for about six months under a doctor's supervision. Doctors are pretty strict about who they will prescribe to, and about the supervision necessary during that time. She had to qualify as obese, have a BMI (body mass index) of at least 30, and have monthly appointments with the doctor. She had to eat nutritiously and slowly increase her exercise. Once she lost enough weight that she dropped out of the "obese" category, the doctor stopped the prescription and my sister went on to lose more weight more slowly on her own.

I think it's primarily used as a tool to help people get moving and make some quick progress with their weight, because being obese has horrible side effects of its own. Phentermine has side effects, but in cases of obesity, the side effects of the medicine may not be as bad as the side effects of the weight, especially if you can lose the weight and then stop the medicine and keep the weight off.

Are you exploring the possibility of using this medicine? Have you spoken with your doctor about it?

Thank you for your question. The Federal Drug Administration (FDA) indicates the following for side effects due to the use of Phentermine:

Phentermine hydrochloride tablets and capsules are indicated only as short-term monotherapy for the management of exogenous obesity. The safety and efficacy of combination therapy with Phentermine and any other drug products for weight loss, including selective serotonin reuptake inhibitors (e.g., fluoxetine, sertraline, fluvoxamine, paroxetine), have not been established. Therefore, coadministration of these drug products for weight loss is not recommended.
Primary Pulmonary Hypertension (PPH) – a rare, frequently fatal disease of the lungs – has been reported to occur in patients receiving a combination of Phentermine with fenfluramine or dexfenfluramine. The possibility of an association between PPH and the use of Phentermine alone cannot be ruled out; there have been rare cases of PPH in patients who reportedly have taken Phentermine alone. The initial symptom of PPH is usually dyspnea. Other initial symptoms include: angina pectoris, syncope or lower extremity edema. Patients should be advised to report immediately any deterioration in exercise tolerance. Treatment should be discontinued in patients who develop new, unexplained symptoms of dyspnea, angina pectoris, syncope or lower extremity edema.
Valvular Heart Disease: Serious regurgitant cardiac valvular disease, primarily affecting the mitral, aortic and/or tricuspid valves, has been reported in otherwise healthy persons who had taken a combination of Phentermine with fenfluramine or dexfenfluramine for weight loss. The etiology of these valvulopathies has not been established and their course in individuals after the drugs are stopped is not known. The possibility of an association between valvular heart disease and the use of Phentermine alone cannot be ruled out; there have been rare cases of valvular heart disease in patients who reportedly have taken Phentermine alone.
Tolerance to the anorectic effect usually develops within a few weeks. When this occurs, the recommended dose should not be exceeded in an attempt to increase the effect; rather, the drug should be discontinued.
Phentermine hydrochloride may impair the ability of the patient to engage in potentially hazardous activities such as operating machinery or driving a motor vehicle; the patient should therefore be cautioned accordingly.
Usage with Alcohol: Concomitant use of alcohol with Phentermine hydrochloride may result in an adverse drug interaction.

Here is the website http://www.drugs.com/pro/phentermine.html.

Here is another website that provides information:

http://www.medicinenet.com/phentermine/article.htm

Is your friend experiencing any side effects now or are you just concerned? I hope this helps.