The quest for effective weight loss solutions has led many to explore various options, including prescription medications and over-the-counter (OTC) diet pills. Phentermine, a prescription medication, is a commonly used aid for weight loss. However, its potential for adverse events and contraindications for individuals with pre-existing medical conditions prompts many to seek safer alternatives, particularly those available over the counter. This article explores the landscape of OTC diet pills, examining their effectiveness, safety, and how they compare to prescription options like phentermine.
Understanding Phentermine and Its Alternatives
Phentermine is a prescription drug chemically related to amphetamine and other central nervous system (CNS) stimulants, used short-term as an aid to weight loss. It impacts food intake by increasing norepinephrine in the body. While effective, it carries potential risks and side effects, including dry mouth, vomiting, and constipation or diarrhea. As a Schedule IV controlled substance, phentermine has the potential for abuse and dependence and should not be used in people with a history of substance use disorder.
Given these concerns, some individuals seek alternatives. These alternatives range from prescription medications to over-the-counter supplements. Newer prescription alternatives to phentermine may help some patients lose weight, but potential side effects are possible for all medications.
Prescription Alternatives to Phentermine
Several FDA-approved prescription medications can serve as alternatives to phentermine. These include:
Contrave: A combination of naltrexone hydrochloride and bupropion hydrochloride, Contrave affects the central nervous system by increasing calories burned and reducing appetite. Naltrexone, an opioid antagonist, and bupropion, an antidepressant, work on two areas of the brain that are involved in the appetite and reward system. Common side effects include nausea, vomiting, diarrhea or constipation, headache, dizziness, insomnia, and dry mouth. Contrave has an FDA-required black box warning due to the risk of suicidal thoughts and behaviors associated with bupropion, its antidepressant ingredient. Patients taking Contrave should be closely monitored for mood changes, suicidal thoughts, or unusual behavior, especially in the first few months of treatment or after dose changes.
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Lomaira: This is a brand-name drug that contains phentermine, but in an 8 mg dose-a smaller dose that is taken three times daily-rather than the typical generic phentermine dose, which is generally a larger dose taken once daily. Lomaira is only available under the brand name.
Saxenda: As a GLP-1 receptor agonist that contains the active ingredient liraglutide, Saxenda is approved for long-term weight management in adults. It is intended to be used indefinitely, in combination with a healthy diet and exercise. Common side effects of Saxenda include stomach problems, including nausea, vomiting, diarrhea or constipation, indigestion, stomach pain, and stomach virus. Other common side effects may include injection site reactions, headache, tiredness, and dizziness. Saxenda has a black box warning. The warning states that the drug causes thyroid C-cell tumors in rats. However, it is not known if Saxenda can cause thyroid tumors in humans. Saxenda should not be used in people with a history (or family history) of medullary thyroid carcinoma or in people with Multiple Endocrine Neoplasia syndrome type 2 (MEN 2).
Wegovy (semaglutide): Wegovy, a weekly injection of semaglutide, reduces appetite and decreases calorie intake. Wegovy slows down stomach emptying, which might affect the absorption of oral medications. It is administered as an injection and approved for use in adults and children aged 12 years or more with obesity (BMI ≥30 for adults, BMI ≥ 95th percentile for age and sex for children) or some adults with excess weight (BMI ≥27) who also have weight-related medical problems. The dose must be increased gradually over 16 to 20 weeks to arrive at the 2.4 mg dosage. This progression can help to alleviate side effects, which include gastrointestinal symptoms, headache, dizziness, and fatigue. The most common side effects of Wegovy include nausea, diarrhea, vomiting, constipation, abdominal pain, headache, fatigue, dyspepsia, dizziness, abdominal distention, eructation, hypoglycemia in patients with type 2 diabetes, flatulence, gastroenteritis, and gastroesophageal reflux disease. It can also cause hypersensitivities such as anaphylaxis, retinopathy in diabetics, heart palpitations, or a racing heartbeat. This drug should not be used by those who are pregnant or who are planning to become pregnant. Personal or family history of medullary thyroid carcinoma (MTC) or patients with multiple endocrine neoplasia type 2 (MEN 2) should not take Wegovy.
Zepbound (tirzepatide): This is a once-weekly injection. It is classified as a glucose-dependent insulinotropic polypeptide (GIP) receptor and glucagon-like peptide-1 (GLP-1) receptor agonist, or GIP/GLP-1 receptor agonist. Because Zepbound affects stomach emptying, check with your healthcare provider if you need to change the timing of any other medicines you take. Also, women who take oral contraceptives (birth control pills) should add a barrier method of birth control (such as condoms) or use another form of effective birth control for 4 weeks after starting Zepbound and for 4 weeks after every dose increase.
Over-the-Counter (OTC) Options for Weight Loss
When purchasing a non-prescription weight-loss aid, it's important to know that while OTC medications are FDA-approved for safety and effectiveness, weight-loss supplements are not. For this reason, be careful when buying an over-the-counter weight-loss pill or popular herbal supplement. The FDA does not approve most of the claims companies make about their products.
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FDA-Approved OTC Medication: Alli (Orlistat)
The only over-the-counter weight-loss pill approved by the FDA is Alli, which contains a lower dose of Orlistat (60 mg), the same medication in Xenical. Alli (pronounced AL-eye) is an over-the-counter drug meant for overweight adults struggling to shed excess pounds. Alli is a 60-milligram, over-the-counter version of orlistat (Xenical), a 120-milligram prescription drug. Food and Drug Administration for use in adults 18 and older who have a body mass index (BMI) of 25 or more. Xenical is approved for use in adults with a BMI of 30 or more (obese).
How it works: Approved by the FDA in 1999, Xenical (orlistat) is a lipase inhibitor. Lipase, an enzyme found in the digestive tract, helps break down dietary fat into smaller parts, so it can be used or stored for energy. Orlistat blocks the work of lipase. When you take the drug with a meal, about 25% of the fat you eat isn't broken down. Undigested fat is then passed through the body.
Effectiveness: One study of 400 people taking 120 mg of Orlistat three times daily reported users significantly reduced their weight, with 27.4% losing at least 5% of their starting weight. Alli may help you lose weight. But the weight loss will likely be modest. In some studies, more than 40% of people taking Alli while following a calorie-restricted diet and increasing physical activity lost 5% or more of their body weight within a year.
Dosage: You take one 60-milligram Alli pill within an hour of a fat-containing meal up to three times a day. You should spread your daily fat intake over the three main meals. Fat intake should be no more than 30% of total calories. If you eat a meal that has no fat, then you don't need a dose of Alli.
Nutrient Absorption: Alli can reduce the absorption of fat-soluble nutrients, including beta carotene and vitamins A, D, E and K. Take a multivitamin at least two hours after your last dose of Alli.
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Side effects: The active ingredient in Alli, orlistat, causes digestive side effects related to undigested fats passing through your digestive system. They generally lessen over time and with proper use of the drug. The most common side effects are gastrointestinal (loose stools and stomach pain) from undigested fat in stools, especially if a low-fat diet is not followed. Orlistat (Alli) can cause changes in bowel habits.
Risks: Orlistat may cause damage to the liver or kidneys. The FDA published a safety review of orlistat in 2010 because of rare reports of serious liver injury in people using it. However, Alli and Xenical labels were revised because of the reports. Alli should not be used by those who are pregnant or breastfeeding, people who have had an organ transplant, those who've been diagnosed with food absorption issues, or those taking cyclosporine.
Other Over-the-Counter Products
Many other over-the-counter products claim to help with weight loss. These products have not been proven to be safe or effective. Other OTC products that claim to help with weight loss haven't been proven to be safe or effective and may be harmful. They may cause heart problems, stroke, kidney problems, cancer, or sexual problems. If you are thinking about trying an OTC weight-loss product, talk to your doctor first.
Glucomannan: The name of this diet supplement may not sound familiar, but you've probably seen products that contain glucomannan, a fiber supplement. Glucomannan is a type of soluble fiber that may be used as a supplement for weight loss. It works by absorbing water and creating a viscous gel that lines the gut, extending the time it takes for your stomach to empty. People taking glucomannan may notice that they burp frequently, feel bloated, and have feelings of stomach fullness-at least for the first few days. Although its effects on weight loss may be inconsistent, some clinical studies suggest a positive effect. A review of six studies involving 225 overweight and obese adults found that taking glucomannan led to an average weight loss of around 2 pounds. When used short-term, glucomannan is typically well tolerated. Mild side effects such as belching, bloating, and stomach discomfort may occur.
Green Tea Extract: Green tea is a popular beverage known for its potential health benefits, particularly related to weight loss. One study found that after 12 weeks of taking a high-dose green tea extract, obese women lost an average of around 2 pounds and had decreases in waist circumference and body mass index (BMI). Green tea is generally well-tolerated. Green coffee is another name for raw coffee beans (so this type of product does contain caffeine). A study of 64 women with obesity found that while they all lost weight on a low-calorie diet, those who received 400mg of green coffee bean extract for eight weeks lost more weight than those who did not take the extract.
Probiotics: Millions of microorganisms, such as bacteria, viruses, and fungi, live in your digestive tract. These microorganisms work together to form what’s known as the gut microbiota, which is important for helping your body break down food and absorb nutrients. Probiotics are beneficial bacteria found in some yogurts and dietary supplements. Although studies on the effects of probiotics on body fat, weight, and waist and hip circumference have found inconsistent results, some research shows that probiotics can support a reduction in body weight and fat percentage. For the most part, probiotics do not cause side effects in healthy individuals.
Garcinia Cambogia: Studies have found garcinia cambogia effective for weight loss regardless of age, gender, or other weight-related conditions. Claims made by sellers have not been supported by scientific research. There is little evidence to support its effectiveness.
Conjugated Linoleic Acid (CLA): One review of seven studies concluded CLA may promote weight loss but the difference in taking this substance versus taking a placebo is relatively small.
Raspberry Ketones: This over-the-counter weight-loss pill became popular after Dr. It is currently unclear whether this dietary supplement offers health benefits. Research suggests raspberry ketones may be associated with coronary vasospasm when the coronary arteries suddenly constrict and reduce blood flow to the heart. Raspberry ketones come from red raspberries (it gives them their smell).
Chromium: Chromium is generally considered safe as long as it is not consumed in high amounts.
Hoodia Gordonii: This herb is extracted from a flowering cactus plant (hoodia gordonii) and sold as an appetite suppressant. In 2014, the FDA flagged Oasis Bee Pollen for making false and misleading claims about its product's weight-loss effects.
Risks Associated with Weight-Loss Supplements
When purchasing a non-prescription weight-loss aid, it's important to know that while OTC medications are FDA-approved for safety and effectiveness, weight-loss supplements are not. For this reason, be careful when buying an over-the-counter weight-loss pill or popular herbal supplement. The FDA does not approve most of the claims companies make about their products.
One study looked at 317 weight-loss products and found 269 (84.9%) contained sibutramine, an ingredient the FDA removed in 2010. The availability of diet pills via the internet has made these substances even harder to regulate and control.
Factors to Consider Before Using Weight-Loss Medications
There are a few factors to think about before buying and using weight-loss medications. Always talk to your doctor about any diet pill or weight-loss supplement you are considering.
Lifestyle Changes
Diet and lifestyle changes are usually the best way to support lasting weight loss and maintenance. Regarding exercise, adults should aim for at least 150 minutes of moderate-intensity activity per week to help decrease body fat, plus two days of muscle-strengthening activity to help build and maintain muscle mass. One way to attain the 150 minutes is to walk for 30 minutes a day, 5 days a week.
Consulting Healthcare Professionals
Consult your healthcare provider. Your healthcare provider is the only one who can determine which medication is best for you, considering your medical and family history, medical conditions, and medications you take that may potentially interact with weight-loss medications. A registered dietitian can be an excellent resource on your weight loss journey, helping you devise a personalized eating plan that considers your nutritional needs, calorie intake, medical conditions, and lifestyle. Diets are not a one-size-fits-all approach.
Insurance Coverage and Cost
Check your formulary, or ask your healthcare provider to check your formulary to see which phentermine alternatives your health insurance plan covers. Insurance coverage varies and will affect many patients’ choices about going on weight loss medications. GLP-1s are notoriously costly. The Kaiser Family Foundation estimates the annual net price of Wegovy at $13,600.
Understanding the Role of BMI
Determining whether someone is a candidate for weight loss medications begins with BMI. For each individual case, the doctor and patient should discuss the patient’s current health issues, other medications, and family medical history. The guidelines for tirzepatide (Zepbound) and semaglutide (Wegovy) state that a patient should have a BMI of 30 or a BMI of 27 with weight-related health problems. Older AOMs also have indications based on BMI and may be contraindicated for use with certain other medications.
The Importance of a Holistic Approach
A treatment plan for obesity can comprise multiple forms of treatment, including medications, diet, exercise, and/or surgery. All weight loss medications work best in the context of a healthy eating plan and exercise. Some weight management medications are designed for short-term use and others for long-term use.
Raghuveer Vedala, MD, FAAFP, Dipl. ABOM, is a board-certified family medicine and obesity medicine physician. His commitment to obesity medicine comes from personal and family struggles with obesity, guiding his holistic approach that connects obesity to health issues, including mental health. He promotes wellness through lifestyle changes, emphasizing exercise, healthy eating, and supportive relationships in addition to traditional metric goals.
The Future of Weight Loss Medications
With fervent consumer demand for weight loss medications, combined with rising obesity rates, more medications are bound for the market in the coming years. Pharmaceutical platform Ozmosi predicts one to two GLP-1 launches annually starting in 2026. specifically for obesity. Lilly is developing at least two new options. The first, orforglipron, is an oral GLP-1 inhibitor that completed a Phase 3 clinical trial in early 2025. It could provide a welcome alternative for people who do not want injections. Phase 3 results expected soon. at 36 weeks. The other, retatrutide, targets GLP-1, GIP, and glucagon. At this writing, it is in Phase 3 clinical trials. In Phase 2, participants lost up to 24.2% of body weight at 48 weeks. Amgen is developing MariTide, a monoclonal antibody designed to increase GLP-1 receptor activity while reducing GIP receptor activity. The once-monthly injection entered Phase 3 clinical trials in March 2025. Researchers continue to study hormones that play a role in appetite for other ways to target obesity with medication. Those of interest include not only GLP-1, but also peptide tyrosine-tyrosine (PYY) and cholecystokinin (CCK). With more options available, doctors will be increasingly able to personalize treatments.