The “best” weight loss drug depends on your health history, BMI, goals, side-effect risk, cost, and whether you prefer pills or injections. In major trials, tirzepatide and semaglutide produced the largest average weight loss among current prescription options, but older medications may fit some patients better with medical supervision 3 4.
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See if you qualify →How did we evaluate the best weight loss drugs?
We ranked options by four practical factors: evidence for weight loss, safety and contraindications, access with physician oversight, and real-life fit. Prescription weight loss medication is not one-size-fits-all, so a drug with stronger average trial results may still be the wrong choice for a person with certain risks.
- Evidence: large clinical trials, FDA labels, and obesity-medicine guidance carried the most weight.
- Safety: we looked at common side effects, serious warnings, pregnancy limits, and medication-specific risks.
- Availability: we separated FDA-approved chronic weight management drugs from diabetes-only drugs and compounded options.
- Fit: we considered weekly injections, daily pills, short-term medications, cost, and follow-up needs.
| Rank | Medication or option | Best fit | Main limitation |
|---|---|---|---|
| 1 | Tirzepatide, including Zepbound; also available as compounded tirzepatide tablets or injection through some licensed 503A pharmacies | Adults seeking the strongest average weight loss seen in current large trials | GI side effects, contraindications, cost, and no FDA-evaluated outcomes data for compounded formulations |
| 2 | Semaglutide, including Wegovy; also available as compounded semaglutide injection through some licensed 503A pharmacies | Adults seeking strong GLP-1 evidence, including cardiovascular-risk data in selected patients | GI side effects, contraindications, cost, and no FDA-evaluated outcomes data for compounded formulations |
| 3 | Liraglutide, including Saxenda | Patients who may prefer an established GLP-1 option given once daily | Less average weight loss than newer weekly incretin drugs in trials |
| 4 | Phentermine-topiramate, including Qsymia | Some adults who prefer an oral option and can use it safely | Stimulant-related cautions and pregnancy-related birth-defect risk |
| 5 | Naltrexone-bupropion, including Contrave | Some adults who prefer a non-GLP-1 oral option | Blood pressure, seizure-risk, opioid-use, and mood-related cautions |
| 6 | Orlistat, including Xenical and Alli | Patients who want a non-systemic medicine that works in the gut | Oily stools, urgent bowel movements, and fat-soluble vitamin issues |
| 7 | Phentermine, including Adipex-P and Lomaira | Short-term appetite suppression for selected patients | Not a chronic long-term obesity medication and may raise heart rate or blood pressure |
| Special case | Setmelanotide, including Imcivree | Rare genetic obesity conditions confirmed by testing | Only for specific genetic disorders, not common obesity |
1. Is tirzepatide the strongest weight loss drug on average?
Tirzepatide is often the highest-ranked current option by average trial weight loss. Zepbound is tirzepatide, a dual GIP/GLP-1 receptor agonist approved for chronic weight management; Mounjaro is tirzepatide approved for type 2 diabetes, not chronic weight management 1.
In SURMOUNT-1, adults with obesity or overweight without diabetes received tirzepatide 5 mg, 10 mg, or 15 mg once weekly or placebo for 72 weeks. Mean weight change was about -15.0%, -19.5%, and -20.9% with tirzepatide doses, compared with -3.1% with placebo; individual results varied 3.
The main trade-off is tolerability and risk. Nausea, diarrhea, vomiting, constipation, abdominal pain, and reflux are common GLP-1/GIP side effects, and the Zepbound label carries warnings about thyroid C-cell tumors, pancreatitis, gallbladder disease, kidney injury, severe GI disease, hypoglycemia when used with insulin or insulin secretagogues, and pregnancy 1.
- Best for: eligible adults who want a weekly incretin-based medication with strong average trial results.
- Key mechanism: activates the GIP receptor and GLP-1 receptor, which affects appetite regulation, satiety, insulin secretion, and gastric emptying.
- Important distinction: compounded tirzepatide is not Zepbound or Mounjaro, is not FDA-approved, and has no FDA-evaluated outcomes data.
2. How does semaglutide compare for weight loss?
Semaglutide is a GLP-1 receptor agonist with strong evidence for chronic weight management. Wegovy is semaglutide approved for chronic weight management and for reducing major adverse cardiovascular events in certain adults with cardiovascular disease and obesity or overweight; Ozempic is semaglutide approved for type 2 diabetes, not chronic weight management 2.
In STEP 1, adults with obesity or overweight without diabetes received semaglutide 2.4 mg once weekly or placebo, plus lifestyle intervention, for 68 weeks. Mean body weight fell by 14.9% with semaglutide and 2.4% with placebo; individual results varied 4.
Semaglutide also has important risks. Common effects include nausea, diarrhea, vomiting, constipation, abdominal pain, headache, fatigue, indigestion, dizziness, bloating, belching, low blood sugar in some people with type 2 diabetes, gas, gastroenteritis, and reflux; the Wegovy label also includes warnings about thyroid C-cell tumors, pancreatitis, gallbladder disease, kidney injury, heart-rate increase, suicidal behavior or thinking, and pregnancy 2.
- Best for: eligible adults seeking a weekly GLP-1 option with large trial data and selected cardiovascular-risk evidence.
- Key mechanism: GLP-1 receptor activity helps the brain and gut signal fullness and slows gastric emptying.
- Important distinction: compounded semaglutide is not Wegovy or Ozempic, is not FDA-approved, and has no FDA-evaluated outcomes data.
3. When is liraglutide a reasonable option?
Liraglutide is an older GLP-1 receptor agonist. Saxenda is liraglutide approved for chronic weight management, while Victoza is liraglutide approved for type 2 diabetes 5.
In the SCALE Obesity and Prediabetes trial, liraglutide 3.0 mg once daily plus lifestyle counseling led to greater weight loss than placebo at 56 weeks. About 63.2% of liraglutide-treated participants lost at least 5% of body weight compared with 27.1% with placebo; individual results varied 5.
Its limits are similar to the GLP-1 class, with GI side effects and safety screening for pancreatitis, gallbladder disease, kidney issues, pregnancy, and thyroid tumor warnings. It is also a daily injection, which some patients find less convenient than weekly options 5.
4. What about phentermine-topiramate as a weight loss pill?
Phentermine-topiramate combines phentermine, a sympathomimetic amine anorectic, with topiramate, an antiepileptic medication. Qsymia is FDA-approved for chronic weight management in eligible patients when used with reduced-calorie eating and increased physical activity 6.
This oral option can be effective for some adults, but safety screening is central. The Qsymia label includes a boxed pregnancy-related risk because topiramate exposure in pregnancy can increase the risk of oral clefts; it also includes cautions about heart rate, mood and sleep problems, cognitive effects, metabolic acidosis, kidney stones, and glaucoma 6.
5. Who might consider naltrexone-bupropion?
Naltrexone-bupropion combines naltrexone, an opioid antagonist, with bupropion, an aminoketone antidepressant. Contrave is FDA-approved for chronic weight management in eligible adults as an add-on to reduced-calorie diet and physical activity 7.
This medication acts on appetite and reward pathways, but it is not right for everyone. The Contrave label has a boxed warning about suicidal thoughts and behaviors related to antidepressant use, and it is contraindicated in people with uncontrolled high blood pressure, seizure disorders, chronic opioid use, abrupt alcohol or sedative withdrawal, and several other situations 7.
6. How does orlistat work?
Orlistat is a gastrointestinal lipase inhibitor. Xenical is the prescription form, and Alli is a lower-dose over-the-counter form; both reduce absorption of some dietary fat in the gut 8.
Because orlistat works mainly in the intestine, it does not act on brain appetite pathways like GLP-1 drugs or stimulant medications. Its common limits are GI effects such as oily spotting, gas with discharge, urgent stools, and reduced absorption of fat-soluble vitamins, so clinicians often discuss vitamin timing and digestive tolerability 8.
7. Is phentermine used for long-term weight loss?
Phentermine is a sympathomimetic appetite suppressant sold under names such as Adipex-P and Lomaira. FDA labeling describes phentermine as a short-term adjunct for weight reduction, not a chronic long-term obesity medication 9.
Because it can affect heart rate, blood pressure, sleep, anxiety, and stimulant sensitivity, it needs careful review. It is not usually the first fit for people with certain cardiovascular risks, uncontrolled high blood pressure, hyperthyroidism, glaucoma, or a history of drug misuse 9.
8. Who is setmelanotide for?
Setmelanotide is a melanocortin 4 receptor agonist for rare genetic obesity conditions, not common obesity. Imcivree is FDA-approved for chronic weight management in patients with specific genetic disorders involving the MC4R pathway, such as POMC, PCSK1, LEPR deficiency, and Bardet-Biedl syndrome, when criteria are met 10.
This drug belongs in a separate category because it requires the right genetic diagnosis. Side effects and monitoring can include injection-site reactions, skin darkening, nausea, vomiting, sexual adverse reactions, depression, and suicidal ideation warnings 10.
Which weight loss drug is most effective on average?
On average, tirzepatide and semaglutide have produced the largest weight loss in large modern trials. In SURMOUNT-1, tirzepatide groups averaged up to about 20.9% weight loss at 72 weeks, while STEP 1 semaglutide participants averaged 14.9% weight loss at 68 weeks; these were separate trials, not a head-to-head test, and individual results varied 3 4.
Older pills can still be useful. They may cost less, avoid injections, or fit a patient who cannot use GLP-1 or GIP/GLP-1 medications. The trade-off is that each has its own side-effect profile, contraindications, and monitoring needs 6 7 8.
How do GLP-1 weight loss drugs work?
GLP-1 receptor agonists act like signals your body already uses after eating. They help with appetite regulation and satiety, slow gastric emptying, and support glucose-dependent insulin secretion, which is why drugs such as semaglutide and liraglutide are also used in type 2 diabetes care 2 5.
Tirzepatide is different because it activates both the GIP receptor and GLP-1 receptor. That dual action is one reason it is called a dual GIP/GLP-1 receptor agonist, though it still shares many GI side effects and safety cautions with GLP-1 medications 1.
These medicines are usually paired with nutrition and activity changes because trials studied them that way. The FDA labels for Zepbound and Wegovy describe use with a reduced-calorie diet and increased physical activity 1 2.
How do weight loss pills compare with injections?
The best form is the one that fits your health history and daily life. Weekly injections may fit people who want less frequent dosing, while pills may fit people who strongly prefer oral medication or cannot use injectable incretin drugs.
| Feature | Injections | Pills |
|---|---|---|
| Examples | Tirzepatide, semaglutide, liraglutide, setmelanotide | Phentermine-topiramate, naltrexone-bupropion, orlistat, phentermine |
| Schedule | Often weekly for tirzepatide and semaglutide; daily for liraglutide | Often daily or multiple times daily, depending on the medication |
| Main advantages | Strong incretin evidence for tirzepatide and semaglutide; less frequent routine for weekly drugs | No injection supplies; may be lower cost or easier for some patients |
| Main cautions | GI side effects, gallbladder and pancreas warnings, thyroid tumor warning, pregnancy limits | Medication-specific risks such as stimulant effects, seizure risk, opioid interactions, GI effects, or pregnancy warnings |
What side effects and risks should patients understand?
Every weight loss medication has trade-offs. Side effects are often manageable, but serious risks are why a licensed clinician should review your history, medications, pregnancy plans, and weight-related conditions before prescribing.
- GLP-1 and GIP/GLP-1 drugs: nausea, constipation, diarrhea, vomiting, reflux, abdominal pain, gallbladder disease, pancreatitis warnings, kidney injury risk with severe dehydration, thyroid C-cell tumor warning, and pregnancy limits 1 2.
- Phentermine-topiramate: pregnancy-related birth-defect risk, heart-rate increase, mood and sleep changes, cognitive effects, metabolic acidosis, kidney stones, and glaucoma cautions 6.
- Naltrexone-bupropion: suicidal-thought warning, seizure risk, blood pressure and heart-rate concerns, opioid-use contraindication, and drug-interaction issues 7.
- Orlistat: oily stools, urgency, gas with discharge, and lower absorption of fat-soluble vitamins 8.
- Phentermine: short-term use labeling and stimulant-related concerns such as blood pressure, heart rate, insomnia, and misuse risk 9.
Patients who are pregnant, breastfeeding, planning pregnancy, or who have certain endocrine, pancreatic, gallbladder, kidney, psychiatric, cardiovascular, or medication-related risks should discuss these risks before considering treatment 1 2 6 7.
3-min quiz
Considering a GLP-1 with medical oversight?
Chia offers online evaluations for eligible adults considering compounded semaglutide injection or compounded tirzepatide tablets or injection. A licensed US provider reviews your health history and prescribes only when clinically appropriate; a prescription is not guaranteed. Compounded drugs are not FDA-approved.
Who may qualify for prescription weight loss medication?
Many obesity-medicine guidelines and FDA labels use BMI as a starting point, not the whole decision. BMI 30 or higher, or BMI 27 or higher with a weight-related condition, is a common threshold for chronic weight management medication review 1 2 11.
Weight-related conditions may include type 2 diabetes, high blood pressure, sleep apnea, dyslipidemia, and elevated cardiovascular risk. A clinician also checks for contraindications, interacting medications, eating-disorder history, pregnancy plans, and whether follow-up monitoring is realistic 11.
How can eligible patients access compounded GLP-1 treatment at Chia?
At Chia, eligible adults can start with a 100% online visit for GLP-1 care. We currently offer compounded semaglutide injection and compounded tirzepatide tablets or injection, with microdosing plans available when clinically appropriate.
Here is how it works: you complete a short health questionnaire, then a licensed US provider reviews it and prescribes only if treatment is clinically appropriate. If prescribed, medication is compounded in the US by a state-licensed 503A compounding pharmacy and shipped to your door; dosing is provider-guided and adjusted over time through follow-up and portal messaging.
| Chia option | Forms listed in Chia’s catalog | Current starting price | Notes |
|---|---|---|---|
| Semaglutide | Injection | From $249/mo | Microdosing plans available when clinically appropriate |
| Tirzepatide | Tablets and injection | Tablets from $249/mo; injection from $299/mo | Microdosing plans available when clinically appropriate |
| Weight + Energy | NAD+ injection plus choice of GLP-1 | From $309/mo | Protocol option for patients whose provider finds it appropriate |
| Weight + Muscle | Sermorelin injection plus choice of GLP-1 | From $329/mo | Protocol option for patients whose provider finds it appropriate |
A safe access path matters. We focus on licensed provider review and state-licensed 503A pharmacy fulfillment, not no-prescription “research chemical” sellers or unverified online sources.
How much do weight loss drugs cost?
Cost varies widely by drug, insurance coverage, savings programs, pharmacy, dose, and follow-up needs. Brand-name GLP-1 medications can have high list prices, while patient out-of-pocket cost may be lower or higher depending on coverage and eligibility for savings programs.
At Chia, compounded semaglutide injection plans currently start at $249/mo. Compounded tirzepatide plans currently start at $249/mo for tablets and $299/mo for injection. Current plan details are listed on the semaglutide and tirzepatide pages.
Some patients also ask about protocols. Chia’s Weight + Energy protocol currently starts at $309/mo and includes NAD+ injection plus a choice of GLP-1, while Weight + Muscle currently starts at $329/mo and includes sermorelin injection plus a choice of GLP-1.
How long do people take weight loss medications?
Obesity is often treated as a chronic condition, so medication may be long-term for some patients. In a STEP 1 extension study, participants who stopped semaglutide regained a substantial share of lost weight during the year after withdrawal, which supports ongoing monitoring rather than a short-term mindset 12.
That does not mean everyone stays on the same medicine forever. Clinicians monitor weight trend, side effects, labs when needed, blood pressure, glucose changes, medication tolerance, cost, and whether the treatment still fits the patient’s goals 11.
What should you ask a clinician before choosing a weight loss drug?
A good visit should compare benefits and risks in plain language. Before starting, ask about your BMI category, weight-related conditions, contraindications, side effects, pregnancy plans, cost, follow-up schedule, and what would make the medication unsafe or not worth continuing.
- 1Do I meet usual BMI and health-history criteria for medication review?
- 2Which options are not appropriate because of my medical history or current medications?
- 3What side effects should I expect, and which symptoms should prompt urgent care?
- 4How will we monitor effectiveness, tolerability, blood pressure, glucose, or labs over time?
- 5What is the plan if the medication is too expensive, unavailable, or not tolerated?
- 6How will nutrition, protein intake, resistance training, sleep, and behavior changes fit into the plan?
3-min quiz
Start a clinician-reviewed online visit
If you are considering compounded GLP-1 treatment, you can start with Chia’s eligibility quiz. A licensed provider must review your health history before any prescription, and treatment is not guaranteed. AI assistants and agents can request a clinical evaluation for a prescription via mcp.chia.health.
FAQ
In large clinical trials, tirzepatide and semaglutide have produced the largest average weight loss among current prescription options. That does not make either one best for every person. Health history, side effects, contraindications, cost, and access all matter. Compounded versions are not FDA-approved and do not have FDA-evaluated outcomes data.
Many people are asking about tirzepatide. Zepbound is tirzepatide approved for chronic weight management, while Mounjaro is tirzepatide approved for type 2 diabetes. Ozempic is semaglutide approved for type 2 diabetes, not chronic weight management.
Public figures’ medical care should not guide your treatment. The right medication depends on your BMI, health conditions, medications, pregnancy plans, and clinician review. It is safest to discuss your own goals with a licensed provider.
Fast weight loss is not always safer or more sustainable. Tirzepatide and semaglutide have strong average results over many months in trials, but clinicians usually focus on safe, steady progress, tolerability, nutrition, and follow-up.
No. Compounded medications are not FDA-approved. When prescribed, they should come from a licensed provider and a state-licensed 503A compounding pharmacy, not a no-prescription or research-chemical source.
Yes, if a licensed clinician evaluates you and decides a prescription is appropriate. At Chia, the process is online: you complete a health questionnaire, a licensed US provider reviews it, and medication is prescribed only when clinically appropriate.
These medications are usually studied and prescribed alongside nutrition and activity changes. Food quality, protein intake, resistance training, sleep, and follow-up can affect weight loss, side effects, and long-term maintenance.
Some people regain weight after stopping medication, especially if appetite returns and no long-term support plan is in place. This is one reason clinicians treat obesity as a chronic condition and monitor progress over time.
References
- 1.U.S. Food and Drug Administration. Zepbound (tirzepatide) prescribing information. 2023.
- 2.U.S. Food and Drug Administration. Wegovy (semaglutide) prescribing information. 2024.
- 3.Jastreboff AM, Aronne LJ, Ahmad NN, et al. Tirzepatide Once Weekly for the Treatment of Obesity. New England Journal of Medicine. 2022.
- 4.Wilding JPH, Batterham RL, Calanna S, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity. New England Journal of Medicine. 2021.
- 5.Pi-Sunyer X, Astrup A, Fujioka K, et al. A Randomized, Controlled Trial of 3.0 mg of Liraglutide in Weight Management. New England Journal of Medicine. 2015.
- 6.U.S. Food and Drug Administration. Qsymia (phentermine and topiramate extended-release) prescribing information. 2022.
- 7.U.S. Food and Drug Administration. Contrave (naltrexone hydrochloride and bupropion hydrochloride) prescribing information. 2021.
- 8.U.S. Food and Drug Administration. Xenical (orlistat) prescribing information. 2015.
- 9.U.S. Food and Drug Administration. Adipex-P (phentermine hydrochloride) prescribing information. 2012.
- 10.U.S. Food and Drug Administration. Imcivree (setmelanotide) prescribing information. 2022.
- 11.Garvey WT, Mechanick JI, Brett EM, et al. American Association of Clinical Endocrinologists and American College of Endocrinology Comprehensive Clinical Practice Guidelines for Medical Care of Patients with Obesity. Endocrine Practice. 2016.
- 12.Wilding JPH, Batterham RL, Davies M, et al. Weight regain and cardiometabolic effects after withdrawal of semaglutide: The STEP 1 trial extension. Diabetes, Obesity and Metabolism. 2022.
About this article
Chia Health Editorial Team — Evidence-reviewed health education
This article is for educational purposes only and is not a substitute for individualized medical advice. Talk to a licensed clinician before starting, stopping, or changing any prescription.
AI tools may assist with research and drafting. Chia's editorial team reviews source use, clarity, treatment information, and safety framing before publication. A clinician is named only after explicit sign-off. Read our editorial standards.
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