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I'm already taking a GLP-1. What should I check?

Four checks for anyone already on semaglutide (Wegovy, Ozempic), tirzepatide (Zepbound, Mounjaro) or another GLP-1, plus what to read next.

GLP Guidebook teamUpdated Oct 12, 20264 min read12 sourcesWritten from published sources
The short answer

Check four things. First, that a prescriber licensed in your state prescribed it, that your pharmacy is state-licensed, and that it's an FDA-approved brand, not a compounded version. Second, that your pen or pills look and work as they should, because fake Ozempic has been found in the US. Third, which side effects need a call to your doctor, and which need 911. Fourth, keep up regular reviews with your prescriber.

Read this page first. It covers the checks that matter once you've started: your prescription, fakes and compounded versions, side effects and reviews. At the end, three guides take you further, in order.
On this page
  1. Check your prescription
  2. Check your medicine is genuine
  3. Side effects to watch
  4. Your reviews
  5. What to read next
  6. Sources

1. Did my prescription come the right way?

All GLP-1 medicines need a prescription, from a prescriber licensed in the state where you are, filled by a state-licensed pharmacy.1,2

The FDA says a safe pharmacy always requires a prescription, has a US address and phone number and a licensed pharmacist, and is licensed by a state board of pharmacy. You can check the license through the FDA's BeSafeRx locator.2

Look at the label on your box: it should name an FDA-approved brand, such as Wegovy, Zepbound or Foundayo.

Red flags

  • "No prescription needed". Safe pharmacies always require one.2
  • A vial labeled with a telehealth company's own name, or "semaglutide" or "tirzepatide" with no brand. That usually means a compounded product, which is not FDA-approved. The FDA has warned telehealth companies over exactly this.3,4 (Zepbound vials from a licensed pharmacy are FDA-approved.)
  • Anything sold for "research use only". The FDA has warned sellers of these products.4
  • Claims that a product is "generic Wegovy" or "the same as Ozempic". There is no FDA-approved generic semaglutide or tirzepatide.4

On a compounded version now? Don't stop or switch on your own: ask your prescriber about moving to an FDA-approved brand, and the right dose to restart on. Guide 6 explains.

2. Is my medicine genuine?

Fake Ozempic pens have been found in the US drug supply chain.

  • December 2023, April 2025 and December 2025. The FDA warned about counterfeit Ozempic pens. For the December 2025 fakes, the expiry date and lot number printed on the left of the label were the tell.5
  • Buy only from a state-licensed pharmacy, with a valid prescription, the FDA says.5

Check the lot number on your pen and box. If anything looks or works differently from usual, show it to your pharmacist, and report it to the FDA's MedWatch program.6 Guide 6 covers fakes and storage.

Don't stop or switch on your own. If you're worried about your pen, ask your prescriber or pharmacist what to use instead and how to restart.

3. Which side effects should I watch for?

Stomach upsets are common early on and usually fade.7 A few symptoms need help fast.

Get help now: call 911 or go to the emergency room if you have:
  • Possible pancreatitis (an inflamed pancreas): severe stomach pain that won't go away, sometimes spreading to your back, with or without vomiting.8
  • Signs of a serious allergic reaction: swelling of your face, lips, tongue or throat; trouble breathing; fainting; or a very fast heartbeat.9
  • Signs of very low sugar, like confusion or drowsiness, if you also take insulin or a sulfonylurea (an older type of diabetes pill).9
If you injected too much, call Poison Control on 1-800-222-1222.10
Call your doctor or prescriber soon, or an urgent care clinic, if you have:
  • Possible gallbladder problems: pain in the upper stomach, yellow skin or eyes, fever, or pale clay-colored stools.9
  • Vomiting or diarrhea that stops you keeping fluids down.9
  • Changes in your vision, if you have diabetes.9
  • Possible thyroid problems: a lump in your neck, hoarseness, or trouble swallowing.8

Report a side effect. Tell your prescriber first. You can also report it yourself to the FDA's MedWatch program, online or by phone on 1-800-FDA-1088.6

On tirzepatide (Zepbound, Mounjaro) and taking the birth control pill? The label advises switching to a non-pill method, or adding a barrier method such as condoms, for 4 weeks after starting and for 4 weeks after each dose increase.11 Having an operation? Tell your doctor and anesthesiologist you take a GLP-1.8

4. When should I review how it's going?

Regularly, and before each dose increase. Ask your prescriber when.

The Wegovy and Zepbound labels set no fixed cut-off for stopping: your prescriber weighs how well it's working and how you tolerate it when choosing the dose to stay on.8,11 On Saxenda, the label says to stop if you haven't lost at least 4% of your starting weight after 16 weeks. For someone who started at 200 lb (91 kg), 4% is 8 lb (3.6 kg).12

If you have diabetes, your doctor will also check your HbA1c (a blood test of your average sugar over 2 to 3 months) and your other diabetes medicines.9

Paying yourself and hoping insurance will cover it later? Ask your plan what its prior-authorization rules are; Guide 6 explains.

Take this to your review

  • The brand, strength and dose you're on, and the lot number
  • Your weight and waist notes since you started
  • Any side effects, and when they happen
  • All your other medicines, including supplements and anything bought online
  • Your questions about the long term, cost and stopping
Life on a GLP-1StoppingBefore you see your doctor

What to read next, in order

These three guides go deeper. Each one ends with a link to the next, so you can read them one after another.

  1. 1Side effects and risksGuide 5 of 9DecideWhat's normal in the first weeks, what isn't, and what helps.
  2. 2Life on a GLP-1Guide 8 of 9Live with itEating enough protein, missed doses, storing pens and traveling, Ramadan and fasting.
  3. 3Stopping and the long termGuide 9 of 9Live with itWhat happens if you stop, and how to plan for the long term.
Was this page easy to understand?

Sources

  1. American Medical Association. How state licensing has evolved to meet telehealth's challenges (physicians "licensed in the state where their patients are receiving their care"). October 12, 2023. ama-assn.org
  2. FDA. How to buy medicines safely from an online pharmacy. Content current as of January 2, 2025. fda.gov
  3. FDA. FDA warns 30 telehealth companies against illegal marketing of compounded GLP-1s (products branded with the telehealth firm's name; claims implying sameness). March 3, 2026. fda.gov
  4. FDA. FDA's concerns with unapproved GLP-1 drugs used for weight loss (compounded drugs not FDA-approved and not generics; "research use only" products). Content current as of October 1, 2026. fda.gov
  5. FDA. FDA warns consumers not to use counterfeit Ozempic (semaglutide) found in US drug supply chain (December 21, 2023, April 14, 2025, December 5, 2025). fda.gov
  6. FDA. MedWatch: the FDA safety information and adverse event reporting program (1-800-FDA-1088). Content current as of October 9, 2026. fda.gov
  7. Wilding JPH et al. Once-weekly semaglutide in adults with overweight or obesity (STEP 1). NEJM, 2021;384:989–1002. DOI
  8. Novo Nordisk. Wegovy (semaglutide) US prescribing information, revised June 2026. Sections 1, 2, 5, 8.3, 17. PDF
  9. Novo Nordisk. Ozempic (semaglutide) injection, US prescribing information and Medication Guide, revised May 2026. PDF
  10. America's Poison Centers. Poison Control: 1-800-222-1222. Checked October 12, 2026. poison.org
  11. Eli Lilly. Zepbound (tirzepatide) US prescribing information, revised August 2026 (maintenance dose; oral contraceptives). uspl.lilly.com
  12. Novo Nordisk. Saxenda (liraglutide) US prescribing information, revised February 2026 (stop if under 4% lost at 16 weeks). PDF

Last checked Oct 12, 2026 · Next review due Jan 2027

How this page was made. Written by the GLP Guidebook team from the sources above: FDA labels and notices, published trials and state-licensing information. It's general information, not medical advice. Talk to your doctor or another qualified prescriber before starting, stopping or changing any medicine. In an emergency, call 911. How we write