Obesity Resource Center

Obesity Prescriptions


What is it? Phentermine often sold under the brand names Adipex-P, Oby-Cap, T-Diet, Lomaira, or Zantryl is a stimulant that acts on the central nervous system (similar to an amphetamine) to suppress appetite for weight loss.

How is it used? Phentermine is prescribed to patients in need of medical intervention to keep weight down (obese patients with comorbidities in particular). The use of this medication must be medically supervised on a temporary, 4-6 week basis in conjunction with a low-calorie diet, exercise regimen, and behavioral modifications for quick weight loss results.

How does it work? Researchers aren’t exactly sure how Phentermine is able to suppress the appetite but due to its effectiveness, the use of Phentermine has allowed patients to more easily restrict calories to speed up weight loss in the short term.

Safety Considerations. Phentermine is a controlled substance that can produce a variety of health risks from the more serious primary pulmonary hypertension and valvular heart disease, to milder symptoms such as heart palpitations, dizziness, edema, and shortness of breath if used for a longer-term than directed.

Phentermine also stimulates neurons to release high amounts of neurotransmitters called catecholamines (norepinephrine in particular). These neurotransmitters stimulate the nervous system, increase blood pressure, and elevate heart rate, creating restlessness and insomnia. Phentermine use must be closely monitored by a doctor to avoid complications that can arise on this medication.



What is it? Qsymia is a weight management medication that reduces cravings and minimizes hunger to break patterns of overeating and impulse-driven eating. Qsymia reportedly facilitates hunger control throughout the day.

How is it used? Qsymia is prescribed to adults with BMIs at 27 or greater, along with the presence of at least one weight-related condition. Qsymia is used on a short-term basis with routine patient evaluation at the 12-week mark. Weight loss must be achieved at 3% body weight by this point, if not the dosage can be increased by a medical professional during an additional 12 weeks of treatment.

How does it work? In conjunction with a diet and exercise program, Qsymia uses two major appetite suppressants, Topiramate and Phentermine to keep users feeling full throughout the day, which causes a significant decrease in calorie consumption. The precise reasons why these two medications are effective for appetite suppression aren’t clear.

Safety Considerations. Doctor supervision and evaluation prior to using Qsymia are necessary. This medication is not safe for pregnant mothers, those who are taking MAOIs, or those who have existing thyroid disorders. Serious side effects such as an increased heart rate, vision problems, suicidal thoughts, mood swings, low blood sugar, seizures, kidney stones, dizziness, constipation, and dry mouth have been known to occur.



What is it? Xenical (Orlistat) is prescribed to patients in need of obesity management to help patients lose weight and reduce risks of weight gain later.

How is it used? Xenical is a gastrointestinal lipase inhibitor that inhibits the absorption of dietary fats.

How does it work? In conjunction with diet and exercise, Xenical can be prescribed to patients with BMIs of 27 or higher who have one or more weight-related conditions such as hypertension, diabetes, or high cholesterol. Xenical comes in 120 mg capsules that are taken three times per day (one with each meal). Since Xenical specifically targets dietary fats, Xenical does not need to be taken with meals that contain no fat. Xenical can be used long-term for weight maintenance under doctor supervision.

Safety Considerations. Xenical is not safe for pregnant patients, those with food and vitamin absorption issues, or those with gallbladder problems. Those with existing medical conditions must disclose them to their doctor to prevent further complications while on this medication. Side effects may include, low vitamin absorption, gastrointestinal distress, kidney problems, gallbladder problems, changes in skin complexion, and changes in urine color.



What is it? Saxenda is an injectable prescription medication for obesity management and long term prevention.

How is it used? Saxenda is prescribed to patients with BMIs of 27 and up who may have other conditions associated with excess weight gain. An injectable pen is used with a gradual increase in daily dosing from 0.6 mg to 3.0 mg within the first five weeks.

How does it work? In conjunction with diet and exercise, Saxenda acts like the glucagon peptide hormone GLP-1 in the body, which regulates the appetite so that fewer calories are consumed throughout the day. Saxenda can be used for long term weight maintenance under a doctor’s care.

Safety Considerations. Patients using Saxenda may be at an increased risk of thyroid tumors, certain cancers, inflammation of the pancreas, low blood sugar, increased heart rate, kidney problems, suicidal thoughts, upset stomach, and dizziness.


What is it? Belviq is a prescribed weight-loss therapy for obese or overweight adults who may also be suffering from weight-related medical conditions in cases where diet and exercise may not be as effective.

How is it used? For patients with BMIs of 27 and up who may have one or more weight-related conditions, Belviq is used in conjunction with diet and exercise to suppress the appetite and create feelings of fullness and satiety, suppressing hunger and food cravings. Belviq 10 mg tablets are taken twice daily, while Belviq 20 mg tablets are to be taken once daily with or without food.

How does it work? Belviq’s active ingredient Lorcaserin suppresses a hunger receptor in the brain. By sending the full signal to the brain more frequently, Belviq may help dieters adjust to lower calorie dieting without the uncomfortable symptoms associated with calorie reduction. It is unclear exactly how Belviq works. Belviq is classified as a controlled substance that may lead to addiction or dependence and is only offered as a short-term option meant to be taken under doctor supervision for up to 12 weeks. Weight loss of at least 5% of a patient’s body weight is expected within that time duration.

Safety Considerations. Belviq must be taken under doctor supervision, as patients who take more than the prescribed dosage, can suffer from hallucinations, dizziness, fatigue, or out-of-body experiences. Those who are pregnant cannot use Belviq, and side effects may include: Serotonin syndrome, valvular heart disease, mental imbalances, memory impairment, irregular or slow heartbeat, low blood sugar, and certain drug interactions.


What is it? Contrave is a weight loss prescription that blocks cravings and hunger while on a reduced-calorie diet.

How is it used? For patients with BMIs of 27 and up who may have one or more weight-related conditions, Contrave is taken on a long term basis for weight loss and weight control. Dosing begins with one pill in the morning and increases to two pills both in the morning and evening by week four (though a doctor might prescribe a different dosing schedule based on patient need). Contrave is meant to be taken in conjunction with a diet and exercise regimen.

How does it work? Contrave contains two medications, bupropion and naltrexone which both work on the brain’s reward system in two areas, the hypothalamus and the mesolimbic reward system to stimulate hunger control. Both medications are used frequently to treat addiction and dependency disorders and appear to be effective in the prevention of overeating as well.

Safety Considerations. Contrave may increase thoughts of suicide and depression, anxiety, changes in mood, and behavior. A range of health conditions ranging from heart problems to kidney disorders must be disclosed to your doctor before Contrave is prescribed to ensure there are no further complications. Side effects of Contrave may include, seizures, an increase in blood pressure or heart rate, low blood sugar, liver damage, kidney damage, stomach upset, dizziness, and vision problems.


What is it? Plenity is prescribed for weight management purposes in adults with BMIs of 25 and over.

How is it used? Plenity comes in capsule form with three taken before lunch and dinner with 16oz of water. Used in conjunction with a diet and exercise plan, Plenity should be taken 20-30 minutes before a meal, but can be taken during or directly after mealtime on a long term basis for weight control.

How does it work? Plenity is made from naturally derived cellulose and citric acid to absorb the water ingested and mixed with food consumed, resulting in feelings of fullness and satiety. This helps with portion control, craving control, and calorie reduction to trigger weight loss results.

Safety Considerations. Plenity may cause gastrointestinal side effects such as constipation, nausea, bloating, indigestion, and diarrhea. Those with Crohn’s disease and diverticulitis and other GI issues will need to disclose this information to their doctor before using Plenity.