Weight loss injections at med spas: semaglutide, tirzepatide, and what to expect

GLP-1 weight loss injections are the fastest-growing category at med spas — many practices now offer semaglutide or tirzepatide alongside their traditional aesthetic services. Here's what patients should know before starting, including the critical aesthetic implications.

What are GLP-1 medications?

GLP-1 receptor agonists are a class of medications originally developed for type 2 diabetes that produce significant weight loss as a primary or secondary effect. The two most relevant for weight management:

Semaglutide:
Brand names: Ozempic (diabetes indication), Wegovy (weight loss indication — FDA-approved for obesity)
Injectable (once weekly subcutaneous)
Average weight loss in clinical trials: 15–17% of body weight over 68 weeks (Wegovy)

Tirzepatide:
Brand names: Mounjaro (diabetes), Zepbound (weight loss — FDA-approved)
Dual GIP/GLP-1 receptor agonist (two mechanisms vs semaglutide's one)
Average weight loss in clinical trials: 20–22% of body weight over 72 weeks (Zepbound)

How they work: These medications slow gastric emptying, reduce appetite centrally, and affect satiety signaling — the result is significantly reduced calorie intake with less effort. They are not stimulants.

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Why med spas offer them

GLP-1 programs at med spas typically involve:
Medical evaluation and prescription by the med spa's medical director or affiliated physician/NP
Ongoing monthly consultations and monitoring
Injection supplies
Often: nutritional coaching, body composition tracking, and combination with body sculpting treatments

The patient overlap is natural: Patients seeking weight loss and body contouring are the same patients med spas already serve. Offering medical weight management creates a complete body transformation service.

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Compounded vs. branded medications

This is the most important distinction in the current market.

FDA-approved branded medications (Wegovy, Zepbound): Manufactured by Novo Nordisk and Eli Lilly respectively under rigorous FDA manufacturing standards. The reference products.

Compounded semaglutide/tirzepatide: Due to drug shortages, the FDA allowed compounding pharmacies to make copies of these medications. Compounded versions are:
Not FDA-approved (compounding itself is legal, but compounded drugs don't go through FDA approval)
May vary in concentration, purity, and inactive ingredients
Cannot be confirmed equivalent in bioavailability to branded
The FDA has flagged concerns about compounded GLP-1 products

2024 status: As the drug shortage designation ended, the FDA warned that compounded versions should no longer be made — though enforcement and practice lag. Many med spas continue to offer compounded versions at significantly lower prices.

Patient consideration: The risk profile difference between compounded and branded is not definitively characterized. However, patients should understand: lower price often means compounded formulation. Ask your provider explicitly what product they're dispensing.

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Candidacy

Appropriate candidates:
BMI ≥30 (obesity) or BMI ≥27 with at least one weight-related condition (hypertension, type 2 diabetes, sleep apnea)
Patients who have attempted lifestyle modifications without adequate response
No contraindications (see below)

Contraindications:
Personal or family history of medullary thyroid carcinoma (MTC)
Multiple endocrine neoplasia syndrome type 2 (MEN 2)
Pregnancy or planning pregnancy
Current pancreatitis or history of pancreatitis
Severe GI motility disorders

Important: At a med spa with appropriate medical oversight, a physician or NP should take a full medical history before prescribing. A prescription without medical evaluation is inappropriate.

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What to expect: the timeline

Weeks 1–4: Dose escalation begins at a low dose to minimize GI side effects. Weight loss is modest at this phase — the body is adjusting.

Months 2–4: Appetite reduction becomes significant. Most patients notice a "food noise" reduction — the constant background thinking about food diminishes. Weight loss accelerates.

Months 4–12: Maximal weight loss phase for most patients. At Wegovy's target dose (2.4 mg semaglutide weekly), most weight loss is achieved by 12–16 months.

Ongoing: Maintenance dosing. Weight tends to return when medication is stopped — these are chronic condition treatments, not courses.

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Side effects

Common (especially during dose escalation):
Nausea (most common — usually decreases with time)
Constipation or diarrhea
Fatigue
Mild headache

Less common but notable:
Vomiting during escalation phase
GERD (acid reflux)
"Ozempic face" — the term for facial volume loss that occurs with significant weight loss (see below)

Serious (rare):
Pancreatitis — abdominal pain radiating to the back; discontinue and seek care
Gallstone formation — accelerated weight loss increases gallstone risk
Thyroid: theoretical risk based on rodent studies; not confirmed in human clinical data

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"Ozempic face" and aesthetic implications

Significant weight loss — from any cause — can cause facial volume loss. GLP-1 medications produce this at scale because of rapid, substantial weight reduction. Patients lose fat from facial fat compartments, which can make them look older, gaunt, or hollow-cheeked even as their body looks better.

Key aesthetic intersections:

Filler during weight loss: Not recommended. The face keeps changing as you lose weight. Filler placed while losing weight may look overcorrected as the face continues to thin. Wait until weight has been stable for 3–6 months before booking filler appointments.

Filler after weight loss plateau: This is the correct timing. Voluma for cheeks, temple filler, or a liquid facelift approach to restore facial volume after the weight loss phase is complete is often the most efficient sequence.

Body sculpting timing: Same principle — body contouring treatments (CoolSculpting, Emsculpt) should wait until weight has been stable for 3–6 months. During active loss, the treatment area keeps changing.

Skin laxity: Significant weight loss can leave loose skin on the face, neck, abdomen, and thighs. Skin tightening devices (Morpheus8, Ultherapy) and potentially surgery are considerations after plateauing.

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Questions to ask before starting at a med spa

Is a physician or NP performing my medical evaluation, or is this a questionnaire-only process?
Are you prescribing the FDA-approved branded medication (Wegovy/Zepbound) or a compounded formulation?
What monitoring do you perform during the program (weight, BP, labs)?
What is the plan if I develop side effects?
What is the long-term plan — do you have a maintenance protocol, or does the program end after a target is reached?

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