7 Things You Must Know Before Using GLP-1 Weight-Loss Drugs — Prescription, Side Effects, Out-of-Pocket Cost, Post-Discontinuation Rebound, and Misuse Cautions

GLP-1 Weight-Loss Drugs Are 'Prescription-Only Medicines,' Not Diet Supplements

Recently, GLP-1-class weight-loss treatments such as Wegovy and Mounjaro have been drawing major attention. However, these drugs are not diet supplements you can freely buy at a pharmacy — they are prescription-only medicines that absolutely require a doctor's diagnosis and prescription. Before approaching them based on efficacy alone, knowing the prescription criteria, side effects, cost, changes after discontinuation, and misuse risks in a balanced way is a safe starting point.

1. What Are These Drugs — Wegovy, Mounjaro, and the Outlook for Oral Pills

• Wegovy (semaglutide, Novo Nordisk): A once-weekly subcutaneous injection, launched in Korea in 2024 with an obesity-treatment indication. Other drugs in the same Novo Nordisk family include Ozempic and Saxenda.
• Mounjaro (tirzepatide, Eli Lilly): A dual-action drug that acts on both GIP and GLP-1 simultaneously, injected once weekly. In Korea it is approved with a diabetes indication (Mounjaro), while in the US it is approved with an obesity indication (Zepbound); its Korean launch falls in the 2024–2025 timeframe.
• Oral GLP-1 weight-loss drugs: Eli Lilly's orforglipron has completed Phase 3 clinical trials and is in the approval-process stage (under development/review). It has not yet been generally launched, and its specific launch date, price, and domestic brand name have not been finalized and may change — check the latest news.

2. How They Work — Appetite Suppression and Delayed Gastric Emptying

GLP-1-class drugs work by mimicking a hormone in our body involved in regulating appetite and blood sugar. The key is that they act on the brain's appetite-control signals to increase satiety and slow the speed at which food leaves the stomach (gastric emptying), giving a feeling of fullness that lasts longer even when eating less. As a result, total calorie intake decreases, which can lead to weight loss. However, this is an aid that 'reduces appetite,' and it does not replace management of diet, exercise, and lifestyle habits.

3. Not a Drug Anyone Can Be Prescribed — Indications and Criteria

These drugs are not for mild, cosmetic weight loss; they are treatments prescribed under a doctor's judgment to patients who meet an obesity (or diabetes, etc.) indication. Generally, eligibility for prescription is determined based on body mass index (BMI) criteria or the presence of comorbidities, and the specific criteria differ by drug and by country, with medical professionals evaluating each individual's condition to decide.

4. Common Side Effects and Rare but Important Risks

• The most common are gastrointestinal side effects — nausea, vomiting, diarrhea, constipation, etc., which tend to appear especially in the early stages when increasing the dose.
• Rarely, pancreatitis and gallstones (gallbladder disease) are reported. If severe abdominal pain persists, you need to see a doctor immediately.
• Boxed warning (the strongest warning): In animal (rodent) experiments, thyroid C-cell tumors were observed, so it is contraindicated in those with a personal or family history of medullary thyroid carcinoma or with Multiple Endocrine Neoplasia type 2 (MEN2).
• Depending on the individual, there may be interactions with other drugs or underlying conditions, so you must tell your medical provider about all medications you are taking.

5. It Can Be Expensive Because It's Out-of-Pocket

GLP-1 drugs prescribed for the purpose of obesity treatment are often prescribed as out-of-pocket (not covered by health insurance), so the self-paid burden can be substantial. Also, it is not a drug you use once and are done with — it tends to require continuous use to maintain its effect, so costs accumulate. Specific prices and coverage status differ by drug, time point, and medical institution, so it is good to confirm the actual cost before prescription. (This article does not assert any specific price.)

6. Weight Can Increase Again If You Stop (Rebound)

Because these drugs work by suppressing appetite while you use them, stopping the drug can cause appetite and weight to return (rebound). Rather than 'lose it once and you're done,' a long-term management perspective is needed, and a discontinuation plan should likewise be established in consultation with medical professionals, together with lifestyle strategies such as diet and exercise. Because the degree of effect and rebound varies greatly between individuals, it is hard to expect that the average figures reported in clinical trials apply identically to everyone.

7. Be Especially Wary of Misuse and Unsupervised Use

• Drugs obtained through abnormal channels such as overseas direct purchase or online buying are dangerous because their authenticity, storage, and dosage cannot be guaranteed.
• If someone who does not meet the indication uses it for cosmetic purposes, or ignores the recommended dose and dose-escalation schedule, the risk of side effects increases.
• There are situations where it must not be used — during pregnancy or breastfeeding, or with certain diseases or a contraindicated medical history. Do not self-judge.
• The drug is not a magic solution, and even clinical averages should be taken cautiously as 'roughly about ~,' presupposing individual variation.

GLP-1 weight-loss drugs can be a promising treatment option, but they are not a 'diet drug safe for everyone.' The key is to decide after weighing the indications, contraindications, cost, and post-discontinuation changes together with medical professionals.

Key Points to Remember (Summary)

1. It is a prescription-only medicine and a doctor's prescription is absolutely required — not a supplement.
2. Wegovy (semaglutide) and Mounjaro (tirzepatide) are injectables; the oral drug (orforglipron) is still in the development/approval stage.
3. It works by reducing intake through appetite suppression and delayed gastric emptying.
4. Common gastrointestinal disturbances, rare pancreatitis and gallstones; a history of medullary thyroid carcinoma/MEN2 is a contraindication.
5. It can be expensive as out-of-pocket, and weight may rebound when stopped.
6. Overseas direct purchase and unsupervised cosmetic use are dangerous — always consult a professional.

Disclaimer

This article is for general medical-information reference and does not replace medical diagnosis or prescription. Starting, stopping, or changing the dose of any medication, including GLP-1 weight-loss drugs, must be decided in consultation with a doctor or pharmacist. Drug information, launch, price, coverage status, etc. may change, so please check the latest official information and your medical provider's guidance.