GLP-1 glossary

47 terms you will meet when researching GLP-1 medications, defined without jargon. Link to any term with its anchor, e.g. /glossary/#incretin.

"Ozempic face": Media shorthand for facial volume loss after rapid weight loss from any cause — not a drug-specific effect. Slower loss and good protein intake blunt it.
503A pharmacy: A state-licensed compounding pharmacy that prepares patient-specific prescriptions. Regulated primarily by state boards of pharmacy.
503B outsourcing facility: An FDA-registered compounding facility held to full manufacturing-grade (CGMP) quality standards — generally the higher quality bar for compounded GLP-1s.
B6-compounded GLP-1: A compounded formulation pairing a GLP-1 (usually semaglutide) with vitamin B6 (pyridoxine), an evidence-backed anti-nausea vitamin, to soften the drug's most common side effect.
BMI (body mass index): Weight (kg) divided by height (m) squared. Standard eligibility gates: ≥30, or ≥27 with a weight-related condition. An imperfect but ubiquitous screening measure.
Boxed warning: The FDA's most prominent label warning. For GLP-1s it concerns thyroid C-cell tumors observed in rodents — relevance to humans is unconfirmed, but contraindications follow from it.
Comorbidity: A weight-related health condition — hypertension, type 2 diabetes, high cholesterol, sleep apnea — that qualifies a person with BMI 27–30 for GLP-1 therapy.
Compounded medication: Medication prepared by a licensed pharmacy for an individual prescription rather than factory-made. Legal and regulated, but not FDA-approved as a product.
Dual agonist: A single molecule activating two receptors — tirzepatide (GIP + GLP-1) is the approved example. Sometimes called a 'twincretin'.
Food noise: The constant intrusive background thinking about food that many people with obesity describe — and that GLP-1 users most often report disappearing on therapy.
Gastroparesis: Significantly delayed stomach emptying. Pre-existing gastroparesis is a contraindication to GLP-1s, which slow emptying further.
GIP (glucose-dependent insulinotropic polypeptide): A second incretin hormone. Tirzepatide activates both GIP and GLP-1 receptors, which appears to produce greater weight loss than GLP-1 activation alone.
GLP-1 (glucagon-like peptide-1): A gut hormone released after eating that signals fullness to the brain, slows stomach emptying, and boosts insulin when blood sugar is high. GLP-1 medications are long-lasting synthetic versions of this hormone.
GLP-1 receptor agonist: The drug class that activates GLP-1 receptors — including semaglutide, liraglutide, and (as part of its dual action) tirzepatide. Often shortened to 'GLP-1s' or 'GLP-1 RAs'.
Hypoglycemia: Dangerously low blood sugar. GLP-1s rarely cause it alone, but the risk rises when combined with insulin or sulfonylureas — those usually need dose reductions.
Incretin: Any gut hormone released after eating that amplifies insulin secretion. GLP-1 and GIP are the two incretins targeted by current weight-management drugs.
Liraglutide: A first-generation, once-daily GLP-1 (Saxenda, Victoza) producing ~8% average weight loss. The first GLP-1 available as a generic.
Maintenance dose: The ongoing dose used to hold weight after reaching goal — often lower than the dose used during active loss.
Medullary thyroid carcinoma (MTC): A rare thyroid cancer seen in rodent GLP-1 studies, driving the class's boxed warning. Personal or family history of MTC (or MEN 2) is an absolute contraindication.
MEN 2 (multiple endocrine neoplasia type 2): An inherited syndrome predisposing to medullary thyroid carcinoma. An absolute contraindication to all GLP-1 medications.
MIC/B12 (lipotropic) injection: An injectable blend of methionine, inositol, and choline with vitamin B12, marketed as supporting fat metabolism and energy. Low-risk, but clinical evidence for added weight loss is weak.
Microdosing (GLP-1): Deliberate use of doses below standard titration ladders, mainly for maintenance, drug-sensitive patients, or relapse prevention. Clinically practiced but not validated by dedicated trials.
Mounjaro: Brand-name once-weekly tirzepatide injection approved for type 2 diabetes; used off-label for weight management.
Off-label prescribing: A clinician prescribing an approved drug outside its FDA-labeled indication (e.g., Ozempic for weight, or microdose protocols). Legal and common, guided by clinical judgment.
Ondansetron (Zofran): A prescription anti-nausea medication often supplied by GLP-1 programs as a backstop for dose-increase weeks, typically 4 mg dissolving tablets as needed.
Ozempic: Brand-name once-weekly semaglutide injection approved for type 2 diabetes; widely used off-label for weight management at doses up to 2 mg.
Pancreatitis: Inflammation of the pancreas — a rare but serious GLP-1 risk. Severe persistent upper-abdominal pain radiating to the back warrants immediate care, and a history of pancreatitis generally rules out GLP-1 use.
Prior authorization (PA): Insurance paperwork requiring your prescriber to justify a GLP-1 before the plan pays. Denials are common and frequently overturned on appeal.
Rapid-dissolve tablet (RDT): A tablet that dissolves under the tongue in minutes — the typical format for compounded sublingual semaglutide and tirzepatide.
Retatrutide: An investigational triple agonist (GLP-1/GIP/glucagon) in phase 3 trials. Not approved and not legally purchasable; widely counterfeited online.
Rybelsus: The FDA-approved daily oral (swallowed) semaglutide tablet for type 2 diabetes. Distinct from compounded sublingual semaglutide.
Saxenda: Brand-name daily liraglutide injection approved for weight management in adults and adolescents 12+.
SELECT trial: The landmark trial showing semaglutide 2.4 mg cut major cardiovascular events by 20% in adults with overweight/obesity and heart disease — the first weight-loss drug to prove cardiac benefit.
Semaglutide: The GLP-1 receptor agonist in Ozempic, Wegovy, and Rybelsus, and the most-prescribed weight-management molecule. Produced ~15% average weight loss in the STEP 1 trial.
Set point: The weight range the body defends through hunger hormones and metabolic adaptation — the reason most diets reverse and a key concept behind long-term GLP-1 maintenance.
SNAC: The absorption-enhancing carrier in Rybelsus that protects swallowed semaglutide from stomach acid long enough for a small fraction to absorb.
STEP trials: The semaglutide 2.4 mg obesity trial program. STEP 1 showed 14.9% average weight loss at 68 weeks; STEP 4 showed continuing therapy preserves loss while stopping reverses it.
Sublingual (SL): Absorbed under the tongue through the oral lining rather than swallowed or injected. Sublingual GLP-1 doses are not interchangeable with injection doses.
SURMOUNT trials: The tirzepatide obesity trial program. SURMOUNT-1 showed up to 20.9% average loss at 72 weeks; SURMOUNT-5 showed tirzepatide outperforming semaglutide head-to-head.
Telehealth: Medical care delivered remotely (video, phone, or structured online intake). The dominant access route for cash-pay GLP-1 programs.
Telogen effluvium: Temporary hair shedding triggered by rapid weight loss or physiologic stress, typically peaking months 3–5 and regrowing once weight stabilizes.
Tirzepatide: The dual GIP/GLP-1 agonist in Mounjaro and Zepbound. Produced up to ~21% average weight loss in SURMOUNT-1 — the most of any approved medication.
Titration: The scheduled, gradual increase of dose over weeks-to-months that lets the gut adapt and keeps nausea manageable. Typically 4+ weeks per step.
Triple agonist: An investigational molecule activating three receptors (GLP-1, GIP, and glucagon). Retatrutide is the leading example, with about 24% average weight loss in phase 2 trials.
Vitamin B12 (cyanocobalamin): A vitamin essential for energy metabolism and nerve function, commonly injected weekly (1000 mcg) in weight programs. Clearly useful when deficient; little evidence of benefit when levels are normal.
Wegovy: Brand-name once-weekly semaglutide injection approved specifically for chronic weight management, with a target dose of 2.4 mg.
Zepbound: Brand-name once-weekly tirzepatide injection approved for chronic weight management and obstructive sleep apnea, in doses up to 15 mg.