A prescription arrives with vocabulary attached: a titration schedule on the printout, an indication section in the pharmacy pamphlet, half a dozen abbreviations in the forum thread you found at midnight. Most explanations of these words are either too technical or too breezy. This page aims for the middle, defining each term in a few plain sentences and saying where you are likely to meet it.
The terms are grouped by the place you encounter them: the hormones and the drugs first, then the words from a prescription, the words from a label, the words from trial reports, and finally the unofficial vocabulary people actually use. Deeper articles sit one link away, and this page earns its keep by being the one worth keeping open in a tab.
The hormones and the drugs
GLP-1, glucagon-like peptide-1, is a hormone released by the intestine in response to a meal. It increases insulin release when glucose is normal or high, slows digestion and acts on appetite. The full story is in What Is GLP-1, the Hormone Behind the Headlines?
Incretin is the family name for the gut hormones, GLP-1 and GIP among them, that rise after eating and increase insulin release in a glucose dependent way. You meet the word in descriptions of how these medicines work, because the whole system is called the incretin system.
GIP, glucose-dependent insulinotropic polypeptide, is the second incretin. It matters here because tirzepatide acts on the GIP receptor as well as the GLP-1 receptor, which is why the newer medicines are described as dual agonists. See GIP and Glucagon: Why Newer Drugs Hit More Than One Receptor.
Receptor agonist is the term for a drug that binds a receptor and switches it on, imitating the hormone that normally does the job. GLP-1 receptor agonist is the class name for semaglutide, liraglutide, dulaglutide and exenatide, and it is the precise phrase behind the shorthand GLP-1s.
Dual and triple agonist describe drugs built to activate more than one receptor. Tirzepatide is a GIP and GLP-1 receptor agonist; retatrutide, still investigational, adds glucagon. More receptors is not automatically better, as Semaglutide vs Tirzepatide: The Differences That Matter for Tracking and Retatrutide: What to Know About the Triple Agonist explain.
DPP-4 is the enzyme that rapidly inactivates GLP-1 and GIP. A separate class of diabetes tablets blocks it, which raises the body's own incretins a little rather than replacing them at the receptor; that distinction gets a whole article in DPP-4 Inhibitors: The Other Way to Raise GLP-1.
Amylin analogue names drugs imitating amylin, a hormone released by the pancreas alongside insulin that slows gastric emptying and reduces appetite, jobs that overlap with GLP-1's. Cagrilintide, used in the investigational combination CagriSema, is one; see Amylin Analogues: The Other Fullness Hormone.
Words from the prescription
Titration is the planned climb from a starting dose to a maintenance dose, in steps over weeks, so the digestive system can adjust. Every major product has its own ladder, mapped in GLP-1 Titration Schedules Explained, Medication by Medication.
Maintenance dose is the dose intended for ongoing use, as opposed to a starting dose. The distinction is practical: Ozempic's 0.25 mg, for instance, is a starting dose and not a maintenance dose, meant to introduce the body to the medicine. You meet the phrase whenever a schedule shows two columns.
Subcutaneous means into the fat layer under the skin, not into muscle or a vein. The approved sites are the abdomen, the front of the thighs and the back of the upper arms, and rotating among them matters; see GLP-1 Injection Site Rotation: Why It Matters and How to Track It.
Half-life is the time it takes for the amount of a drug in the body to fall by half. Semaglutide's is about one week, tirzepatide's about five days, liraglutide's about 13 hours, which is why some of these medicines are weekly and some daily. The concept gets a full walkthrough in Semaglutide Half-Life: Understanding Your Medication Level.
Steady state is the plateau a medication level reaches after roughly four to five half-lives, about a month for the weekly drugs. It explains why week one and week five can feel different with no dose change in between; Steady State in Plain English: Why Week Five Feels Different covers it properly.
Authorized generic vs generic distinguishes two things people collapse. An authorized generic is the brand product sold without the brand name by arrangement with the original manufacturer; a generic approved through an abbreviated application is a different company's copy. The wrinkle, and which GLP-1 actually has a generic, is in Generic Liraglutide: The First Generic GLP-1.
Compounded describes medication prepared by a compounding pharmacy rather than manufactured and approved as a finished product. The regulatory situation varies, and neither promotion nor panic is the right response; what changes practically is the care logging takes, as Tracking Compounded Semaglutide: Extra Care, Extra Notes lays out.
Words from the label
Indication is the specific use the FDA has approved, in the specific population studied. A drug can work for something it is not indicated for; the indication is a statement about what evidence was submitted and reviewed, not a statement about biology.
Off-label describes prescribing outside that approved indication. It is legal for a prescriber to do, and common. It is not the same as unapproved or compounded, two entirely different situations that sometimes get mixed together in casual usage.
Contraindication is a situation where a drug must not be used. On the semaglutide labels, for example, a personal or family history of medullary thyroid carcinoma, or Multiple Endocrine Neoplasia syndrome type 2, or a prior serious hypersensitivity reaction to the drug.
Boxed warning is the FDA's most serious warning, printed in a box at the top of the label. The GLP-1 class carries one about thyroid C-cell tumors: in rodents, semaglutide caused dose dependent and treatment duration dependent tumors, and the label states it is unknown whether it causes them in humans, because the human relevance of the rodent finding has not been determined. That is the warning, reported exactly as the label frames it.
Accelerated approval is approval granted on a measure expected to predict real clinical benefit, with a confirmatory trial still required. Wegovy injection's MASH indication is one, as explained in GLP-1s and Fatty Liver: What the Trials Report.
Adverse reaction is the label's term for an unwanted effect observed in trials, typically reported with the percentage of participants who had it alongside the placebo percentage. Those two numbers are the difference a label attributes to the drug, and reading one without the other is the classic misreading.
Limitations of use is the label section saying where a drug was not studied or should not be used. It is where you learn, for instance, that a diabetes tablet was never studied in people with a history of pancreatitis.
Excipient is an inactive ingredient in a formulation. The word appears because hypersensitivity contraindications name the excipients as well as the drug itself, so an allergy question is not always about the active molecule.
Words from the trials
Placebo controlled and double blind describes a trial where one group receives an inactive substitute and nobody, participant or investigator, knows who got the drug until the code is broken. The design exists so that expectation cannot quietly produce the result.
Relative vs absolute risk reduction is the distinction behind every scary or exciting trial headline. A 20 percent relative reduction means the rate in the treated group was 20 percent lower than the placebo group's rate, which is a different and usually much smaller number than the change in a person's own odds. GLP-1s and the Heart: What the Outcome Trials Showed works through it.
MACE, major adverse cardiovascular events, is the combined outcome cardiovascular trials count: cardiovascular death, non-fatal heart attack and non-fatal stroke. It turns several rare events into one countable number, at the cost of hiding which events made up the difference.
Endpoint is the outcome a trial was designed to measure, chosen before the trial starts. When a result surprises, the first question an honest reader asks is whether it was the endpoint or something the trial noticed later.
Confidence interval is the range the true value is likely to sit in, given the data. A wide interval means the trial could not pin the answer down precisely; a narrow one means the estimate is stable. It is the number that keeps a single percentage honest.
Words people use that are not official
Food noise is a colloquial term for intrusive, recurring thoughts about food. It is not a clinical diagnosis, which is part of why it is hard to study and easy to relate to; Food Noise: What It Is and How GLP-1s Change It covers what users report.
Ozempic face is a media coinage for facial volume loss during rapid weight loss. It is not an effect specific to any product, since any rapid loss can produce it; see Ozempic Face: What Is Actually Happening.
Plateau is not a technical term, but the pattern it names is real and expected: the deficit that drove loss narrows as the body shrinks. For the practical version, Hit a Plateau on a GLP-1? What Your Data Can Tell You, and for the physiology underneath, Why Weight Loss Always Slows Down.
Non-scale victory is community shorthand for progress the scale cannot show: stairs without pausing, a ring that fits again, a blood pressure medication a prescriber was able to reduce. The idea gets its due in Non-Scale Victories: The Progress Your Scale Misses.
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Frequently asked questions
What does GLP-1 stand for?
Glucagon-like peptide-1. It is a hormone released by the intestine in response to a meal, and it increases insulin release and lowers glucagon when blood glucose is normal or high, while also slowing digestion and acting on appetite centers in the brain. The medicines called GLP-1s are receptor agonists, drugs built to switch on the receptor for this hormone rather than being the hormone itself.
What is the difference between a GLP-1 and a receptor agonist?
In everyday usage they are the same thing: people say GLP-1 and mean a GLP-1 receptor agonist. Strictly, an agonist is a drug that binds a receptor and switches it on, imitating the hormone that normally does. Semaglutide, liraglutide, dulaglutide and exenatide are GLP-1 receptor agonists, which is the precise class name for what prescriptions, labels and forums abbreviate to GLP-1s.
What does titration mean on a GLP-1 prescription?
It is the planned climb from a starting dose to a maintenance dose, in steps over weeks, designed to let the digestive system adjust and to keep side effects manageable. It has nothing to do with the chemistry-lab sense of the word. The steps and their timing belong to the prescriber; a tracker is useful precisely for remembering which week of which step you are in.
What does off-label prescribing mean?
Prescribing a medicine outside the use the FDA has approved it for. It is legal for a prescriber to do, and common across medicine, because approved drugs can have plausible uses nobody has run trials for. It is not the same as unapproved or compounded products. What it means for the reader is simply that the label does not describe the reason, and the prescriber is the one to ask about it.
What is the boxed warning on GLP-1 medications?
The boxed warning is the FDA's most serious warning class, printed in a box at the top of the label. The GLP-1 class carries one about thyroid C-cell tumors: in rodents, semaglutide caused dose dependent and treatment duration dependent thyroid C-cell tumors, and the label states it is unknown whether the medicine causes them in humans, because the human relevance of the rodent finding has not been determined. Reported exactly as written, neither softened nor dramatized.