Tirzepatide (sold as Zepbound) currently produces the largest average weight loss of any FDA-approved injection, making it the top performer by clinical results. But “best” depends on more than raw numbers. Your insurance coverage, medical history, and how your body responds to a specific drug all play a role. Three injectable medications dominate the weight loss landscape right now: Zepbound, Wegovy, and the older daily injection Saxenda. Here’s how they compare.
The Three FDA-Approved Options
The FDA has approved three injectable medications specifically for chronic weight management in adults. All three require a prescription, a BMI of 30 or higher (or 27 with at least one weight-related condition like high blood pressure, type 2 diabetes, or high cholesterol), and are meant to be used alongside diet and exercise changes.
Zepbound (tirzepatide): A once-weekly injection that mimics two gut hormones, GLP-1 and GIP. It’s the newest and most effective option, approved for adults only. Clinical trials showed participants losing roughly 20% or more of their body weight on the highest dose. It’s the same active ingredient found in the diabetes drug Mounjaro.
Wegovy (semaglutide): A once-weekly injection that mimics GLP-1 alone. Approved for adults and children 12 and older. In trials, participants typically lost around 15% of their body weight. The same active ingredient, at different doses, is sold as Ozempic for type 2 diabetes.
Saxenda (liraglutide): A daily injection, also targeting GLP-1. Approved for adults and children 12 and older. In a large clinical trial published in the New England Journal of Medicine, participants lost an average of 8.4 kg (about 18.5 pounds) over 56 weeks, with 63% losing at least 5% of their body weight and 33% losing more than 10%. That’s meaningful, but noticeably less than what the newer weekly options deliver.
Why Zepbound Leads the Pack
Zepbound’s edge comes from its dual-hormone approach. While Wegovy and Saxenda activate only GLP-1 receptors, Zepbound activates both GLP-1 and GIP receptors. This combination appears to suppress appetite more effectively and influence energy regulation through multiple pathways at once. In head-to-head comparisons, tirzepatide has consistently outperformed semaglutide in total weight loss.
That said, Wegovy remains a strong option, especially if your insurance covers it but not Zepbound, or if you respond well to it. Some people plateau on one medication and do better switching to another. The “best” injection in practice is often the one you can access, afford, and tolerate.
How These Injections Work
All three medications mimic hormones your gut naturally releases after eating. These hormones signal your brain to reduce hunger and increase feelings of fullness. The drugs act on brain regions that control appetite, making it easier to eat less without feeling deprived. Many people describe the experience as “food noise” going quiet: the constant background urge to eat simply fades.
Beyond the brain, these drugs slow how quickly your stomach empties, so meals keep you satisfied longer. They also improve blood sugar control by boosting insulin release and dialing back glucagon, a hormone that raises blood sugar. This is why the same active ingredients are also approved as diabetes treatments under different brand names.
What the Dose Schedule Looks Like
You don’t start at the full dose. Both Wegovy and Zepbound use a gradual titration schedule to minimize side effects, particularly nausea.
Wegovy starts at 0.25 mg per week, increasing by 0.25 mg every four weeks until you reach the maintenance dose of 2.4 mg. The full ramp-up takes about 16 to 20 weeks. Zepbound starts at 2.5 mg weekly, increasing by 2.5 mg every four weeks up to a maximum of 15 mg, over a similar timeframe. Your prescriber may keep you at a lower maintenance dose (5 mg or 10 mg for Zepbound) if you’re losing weight steadily and tolerating the medication well.
Saxenda works differently. It’s a daily injection, starting at 0.6 mg and increasing weekly until reaching 3.0 mg. For many people, the convenience of a once-weekly shot is reason enough to choose Wegovy or Zepbound over Saxenda.
Cost Without Insurance
Both Wegovy and Zepbound are available directly from their manufacturers at $499 per month for people paying out of pocket, with Zepbound’s starter dose of 2.5 mg costing $349 per month. These prices represent a significant drop from the original list prices, which were over $1,000 monthly.
Insurance coverage varies widely. Some plans cover these medications only for diabetes, not weight loss. Others require prior authorization, proof of a qualifying BMI, or documentation that you’ve tried other approaches first. Check with your insurer before assuming coverage, as the out-of-pocket difference can be substantial.
Side Effects to Expect
Nausea is the most common side effect across all three medications, especially during the dose-titration phase. Vomiting, diarrhea, constipation, and abdominal discomfort are also frequent. These symptoms tend to be worst in the first few weeks at each new dose level and improve as your body adjusts. Eating smaller meals and avoiding greasy or heavy foods can help.
All three medications carry a boxed warning about a rare type of thyroid cancer called medullary thyroid carcinoma. In animal studies, these drugs caused thyroid tumors. The risk in humans isn’t fully established, but you should not use any of these injections if you or a close family member has a history of medullary thyroid cancer or a condition called multiple endocrine neoplasia syndrome type 2.
Pancreatitis is another concern. FDA labeling warns that acute pancreatitis has been observed in patients taking GLP-1 medications, and treatment should be stopped immediately if it’s suspected. People with gallbladder disease, very high triglycerides (above 1,000 mg/dL), heavy alcohol use, or a smoking habit face higher pancreatitis risk and should discuss these factors with their prescriber before starting.
Compounded Versions: A Real Risk
The high cost and supply shortages of brand-name injections have fueled a market for compounded semaglutide and tirzepatide, often available through telehealth platforms and online pharmacies at lower prices. These are not FDA-approved, meaning no federal agency has verified their safety, effectiveness, or quality before they reach you.
The FDA has flagged several serious concerns. Some compounded injectables have arrived without proper refrigeration, which can degrade the drug. Others contained fraudulent labeling. Dosing errors have led to hospitalizations, sometimes because patients measured incorrect amounts from multi-dose vials, and sometimes because providers miscalculated doses. Some compounded products use salt forms of semaglutide (like semaglutide sodium or semaglutide acetate) that are chemically different from the active ingredient in approved drugs, with unknown safety profiles.
Because state-licensed pharmacies aren’t required to report adverse events to the FDA the way manufacturers are, problems with compounded versions are almost certainly underreported. If you’re considering a compounded option to save money, understand that you’re accepting unknown risks around purity, potency, and sterility.
What Happens When You Stop
Weight regain after stopping these medications is common. Studies consistently show that most people regain a significant portion of lost weight within a year of discontinuation. These drugs don’t permanently reset your appetite or metabolism. They work while you take them, which is why they’re classified as chronic weight management medications, not short-term treatments. Many people plan to stay on them long-term, similar to how someone with high blood pressure stays on medication indefinitely.
This makes cost and access especially important considerations. Choosing a medication you can sustain financially and logistically over years, not just months, matters as much as which one produces the most dramatic initial results.