Getting on weight loss medication starts with meeting specific eligibility criteria and finding the right prescriber. The standard threshold is a BMI of 30 or higher, or a BMI of 27 or higher with at least one weight-related health condition like type 2 diabetes, high blood pressure, or sleep apnea. If you meet those criteria, the process involves a medical evaluation, bloodwork, and often an insurance prior authorization before you fill your first prescription.
Who Qualifies for Weight Loss Medication
The FDA has approved six medications for long-term weight management: orlistat (Xenical/Alli), phentermine-topiramate (Qsymia), naltrexone-bupropion (Contrave), liraglutide (Saxenda), semaglutide (Wegovy), and tirzepatide (Zepbound). A seventh, setmelanotide, is only for people with confirmed rare genetic conditions. Phentermine on its own is approved for short-term use, meaning less than 12 months.
The eligibility rules are consistent across most prescribers and insurance plans. You need either a BMI of 30 or greater, which qualifies on its own, or a BMI of at least 27 paired with a weight-related condition. Qualifying conditions typically include coronary heart disease, high cholesterol or triglycerides, blood pressure above 140/90, obstructive sleep apnea, or type 2 diabetes. Pregnancy is a universal exclusion.
Certain medical histories can disqualify you from specific medications. GLP-1 drugs like Wegovy and Zepbound are not appropriate for anyone with a personal or family history of medullary thyroid cancer or multiple endocrine neoplasia syndrome type 2. They’re also not recommended for people with severe gastrointestinal conditions, including severe gastroparesis. If you have a history of pancreatitis, your doctor will weigh the risks carefully since these medications haven’t been studied in that population.
Which Doctor to See
Your primary care doctor can prescribe weight loss medication, but specialists tend to offer more thorough management. The American Medical Association recommends seeking out a physician who is board-certified in obesity medicine, an endocrinologist, or a gastroenterologist. These providers understand how the medications work, how to adjust doses, and how to monitor you for side effects over time.
This matters because these drugs aren’t a one-and-done prescription. The dosing starts low and increases gradually over weeks or months. During that titration period, your provider may need to slow down the dose increases or temporarily reduce your dose based on how you’re tolerating the medication. A provider who regularly manages these drugs will catch problems earlier and keep your treatment on track.
What Happens at the First Visit
Expect your initial appointment to be a comprehensive medical evaluation, not just a weigh-in. Your doctor will review your full medical history, looking for conditions like uncontrolled blood pressure, insomnia, vision changes, and gastrointestinal symptoms. Some of these issues may need to be addressed before starting a weight loss medication, and others will influence which drug is the best fit for you.
You’ll also need baseline blood work. The standard panel before starting a GLP-1 medication typically includes:
- Blood sugar: a fasting glucose test and HbA1c, which shows your average blood sugar over the past two to three months
- Kidney function: creatinine and eGFR tests to check how well your kidneys are filtering
- Liver function: ALT and AST enzyme levels
- Thyroid: TSH to make sure your thyroid is working properly
- Cholesterol: a full lipid panel covering LDL, HDL, and triglycerides
- Complete blood count: checking red blood cells, white blood cells, and platelets
Some providers also test vitamin D, B12, iron, and magnesium levels, especially since these medications reduce appetite and can lead to nutritional gaps. If there’s concern about pancreatitis risk, your doctor may also check pancreatic enzyme levels. Once you’re on a stable dose, expect repeat blood work every three to six months.
Getting Through Insurance Approval
Most insurance plans that cover weight loss drugs require prior authorization, which means your doctor’s office submits documentation proving you meet specific criteria before the pharmacy can fill the prescription. This is where many people hit a delay.
Your prior authorization request will typically need to include your current height and weight, the specific drug name, dose, and frequency, and evidence that the medication will be used alongside caloric restriction, increased physical activity, and behavioral changes. Some plans require documentation that you’ve already attempted lifestyle modifications before approving medication. If you’re reauthorizing after the first year, you’ll need to show that the treatment is working, usually defined as a measurable reduction in body weight from your starting point. Approval periods are commonly 12 months at a time.
If your plan denies coverage, ask your doctor’s office to file an appeal. Many denials are reversed when additional documentation is provided. You can also check whether your plan covers a different medication in the same class, since formulary preferences vary widely between insurers.
What to Expect for Cost
Without insurance, these medications are expensive, often over $1,000 per month at retail price. With insurance coverage and a manufacturer savings card, costs drop significantly. Wegovy’s savings program, for example, can bring your copay down to as little as $25 per month for people with eligible insurance. The manufacturer offers savings options for people without insurance as well, though the discount is smaller.
If cost is a barrier, two resources worth checking are the Medicine Assistance Tool and NeedyMeds, both of which aggregate patient assistance programs, savings cards, and insurance navigation tools. Your doctor’s office or pharmacist can also help identify options specific to your situation.
Why Compounded Versions Are Risky
With high demand and limited supply, compounded versions of semaglutide and tirzepatide have flooded the market. These are not FDA-approved products, and the FDA has flagged serious concerns about them. Some compounded injectables have arrived at patients’ doors warm or without adequate refrigeration, which compromises the drug’s quality. The FDA has also identified fraudulent products with fake pharmacy names on the labels, meaning no one actually verified what’s inside the vial.
Dosing errors are a particular problem. The FDA has received multiple reports of hospitalizations tied to patients or even healthcare professionals miscalculating doses of compounded semaglutide. Some compounders have also prescribed doses beyond what the FDA-approved labeling supports, either higher single doses, more frequent injections, or faster dose increases. The resulting side effects, including severe nausea, vomiting, diarrhea, and abdominal pain, have sent patients to emergency rooms.
There’s another layer of concern: some compounded semaglutide products use salt forms of the drug, like semaglutide sodium or semaglutide acetate. These are chemically different from the active ingredient in approved medications, and the FDA has no data confirming they behave the same way in the body. Two other compounds sometimes marketed for weight loss, retatrutide and cagrilintide, cannot legally be used in compounding at all and have not been found safe or effective for any condition.
What Ongoing Treatment Looks Like
Getting the prescription is just the starting point. These medications require consistent follow-up, not just for safety monitoring but because the lifestyle component is essential to long-term results. Your provider will be tracking whether you’re eating enough (not just less), getting weight-bearing exercise, and managing any side effects that emerge as doses increase.
The titration period, where your dose gradually increases to the target level, can take several months depending on the medication. During this time, gastrointestinal side effects like nausea are common and often improve as your body adjusts. If side effects are severe, your provider may hold at a lower dose longer before increasing. Kidney function gets extra attention during dose changes, particularly if you’re experiencing vomiting or diarrhea, since dehydration from these side effects can stress the kidneys.
Weight loss medications work best as part of a broader plan. The prescription gets the ball rolling, but sustaining the results depends on the habits you build alongside it.