Updated: October 1, 2020
By Doris Munoz-Mantilla, MD, FOMA
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Weight loss medications are an important component of a complete treatment plan for adults with obesity (BMI > 30) or overweight (BMI > 27) with increased adiposity complications. The benefits of weight loss medications include: appetite control, improvement of eating behavior, and slow progression of weight gain and regain.
Before 2012, there were few weight loss medications approved by the U.S. Food and Drug Administration (FDA). The top medications at that time were phentermine and orlistat.
Currently Available Weight Loss Medications
Phentermine (Adipex, Ionamin, Suprenza) and diethylpropion are the oldest medications for weight loss. Phentermine is available in daily doses of 37.5 mg, 30 mg,15 mg, and 8 mg (Lomaira). Phentermine is FDA-approved for short term use, and it is an adrenergic agonist that produces appetite suppression. Side effects include: dry mouth, insomnia, dizziness, and irritability. Caution should be used in patients with hypertension.
Orlistat is a weight loss pill that inhibits pancreatic and gastric lipase decreasing fat absorption in the gastrointestinal tract. It is available to be taken with meals in doses of 120 mg (Xenical) and 60 mg (Alli) OTC. Side effects include: flatulence with fatty discharge and fecal urgency after consumption of high-fat foods, side effects that lead to medication discontinuation.
Since 2012, the FDA has approved four safe weight loss medications for long-term weight management.
Phentermine-Topiramate extended release (Qsymia) is the most effective weight loss drug available to date. It combines an adrenergic agonist with a neurostabilizer. Daily doses with four strengths start at 3.75/23mg to 15mg/92mg. Adults with migraines and obesity are good candidates for this weight loss medication. Side effects include: abnormal sensations, dizziness, taste alterations, insomnia, constipation, and dry mouth. Contraindications include: uncontrolled hypertension and coronary artery disease, hyperthyroidism, glaucoma, and sensitivity to stimulants. If more than 5% weight loss is not achieved after 12 weeks of the maximum dose, the weight loss pill should be gradually discontinued.
Bupropion/Naltrexone (Contrave) combines a dopamine/norepinephrine reuptake inhibitor and an opioid receptor antagonist. Start with a daily dose of 8/90 mg tablet to four tablets a day. It controls cravings and addicted behaviors related to food. Side effects include: constipation, headaches, insomnia, and dry mouth. Contraindications include: uncontrolled hypertension, history of seizures, and opioid use and dependence.
Liraglutide (Saxenda) is a glucagon-like peptide 1 (GLP-1) receptor approved for diabetes type 2 as Victoza and for weight loss injection as Saxenda. Doses start at 0.6 mg to 3 mg a day. Liraglutide delays gastric emptying and causes satiety. Good candidates are adults with diabetes and prediabetes. Side effects include: nausea, vomiting, diarrhea, constipation, and abdominal pain. It is contraindicated in patients with personal or family history of medullary thyroid carcinoma.
Obesity medications are intended for long-term use, as obesity is a chronic disease. They improve health, quality of life, and body weight in patients with overweight and obesity.
Medications for weight loss are only one component of a comprehensive treatment plan that also includes nutritional, physical activity, and behavioral therapies.
Frequently Asked Questions
What are the differences between OTC and prescription weight loss medications?
The medicines currently available are appetite suppressants in some form. They help control hunger and cravings, so you can stick to your nutrition and exercise plan. The only FDA-approved over-the-counter medicine for weight loss is Alli (orlistat). This blocks the body’s ability to absorb fats. The remainder of over-the-counter products are considered supplements. They are not regulated by the FDA and do not have proper studies to confirm their safety and effectiveness. There are prescription medicines that help with weight loss: Qsymia (phentermine/topiramate), Contrave (bupropion/naltrexone), and Saxenda (liraglutide). These are only available through a prescription from a healthcare provider. Each one has certain indications based on the medical evaluation. Obesity is a chronic disease that caused by multiple factors and is the leading risk factor for numerous other medical conditions. Therefore, it is important that your healthcare provider works with you to ensure you are on the safest and most effective medication.
What is the connection between antidepressant medication and weight loss?
Many antidepressants are weight-positive (cause weight gain), some are weight-neutral, and at least one is weight-negative (cause weight loss). When starting an antidepressant, it is a good idea to speak with a healthcare provider about the different options and find a medication that will not cause weight gain. Antidepressants are broken down into categories: selective serotonin reuptake inhibitors (SSRIs), serotonin and norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants, monoamine oxidase inhibitors (MAO inhibitors), and others. Medications within each of these categories can cause weight gain. In the SSRI group, Paroxetine shows the highest associated weight gain. Other SSRIs, including Citalopram (Celexa), Escitalopram (Lexapro), Fluoxetine (Prozac), and Sertraline (Zoloft), have variable effects on weight, and some do not show weight gain until after six months of use. Weight-positive medications in the tricyclic antidepressant category include Amitriptyline, Doxepin, and Imipramine. Desipramine, Nortriptyline, and Protriptyline have variable effects on weight. Bupropion (Wellbutrin), an aminoketone, is considered weight-negative and is prescribed both to assist in weight loss and to treat depression. However, people respond to antidepressants differently. If a person’s depression can be controlled with a weight-negative or weight-neutral antidepressant, they will likely take the medication more consistently, resulting in better efficacy.
Which weight loss medications are known for suppressing appetite?
The following FDA-approved medications suppress appetite: Liraglutide (Saxenda™), Naltrexone-Bupropion (Contrave™), Phentermine-Topiramate (Qysmia™), as well as these stimulants: benzphetamine (Didrex™), diethylpropion (Tenuate™), phentermine (Adiphex-P™, ProFast™), and phendimetrazine. Each medicine impacts appetite differently. Liraglutide is an injectable medication that acts on hormones from the gut that send signals to the brain to make you feel full quicker and decrease hunger signals. Lorcaserin is an oral medication that makes you feel full sooner by acting on serotonin, a neurotransmitter, in a part of the brain that controls appetite. Naltrexone-bupropion also works in the brain, but on the pleasure-reward areas, to decrease cravings and appetite. Phentermine-topiramate is a combination of two medications that work together to decrease appetite and cravings. Topiramate also alters taste sensation, making food less enjoyable for some. The stimulants all work in the brain to decrease appetite. All weight loss medications work best in the context of a healthy eating plan and exercise.
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