Ozempic contains one active ingredient: semaglutide, a lab-modified version of a hormone your body already makes called GLP-1. Each milliliter of the injectable solution contains semaglutide along with a short list of inactive ingredients that keep the drug stable, sterile, and at the right pH. Ozempic is not insulin, though the pen-style injector looks similar.
The Active Ingredient: Semaglutide
Semaglutide is a synthetic copy of glucagon-like peptide 1 (GLP-1), a gut hormone that helps regulate blood sugar and appetite. Your body releases natural GLP-1 after you eat, but it breaks down within minutes. Semaglutide has been chemically altered to last much longer, which is why you only inject Ozempic once a week instead of multiple times a day.
Three key changes make semaglutide different from natural GLP-1. Two amino acids in the peptide chain have been swapped out: one at position 8 (replaced with a synthetic amino acid) and one at position 34 (replaced with arginine). These substitutions protect semaglutide from being chopped apart by an enzyme called DPP-4, which normally destroys GLP-1 within minutes. The third change is the most important: a fatty acid chain is attached to the peptide at position 26. This fatty acid acts like an anchor, latching onto albumin, a large protein floating in your blood. Once bound to albumin, semaglutide is shielded from being filtered out by the kidneys or broken down by enzymes. More than 99% of semaglutide molecules in your bloodstream are bound to albumin at any given time, which gives the drug its long half-life and makes weekly dosing possible.
How Semaglutide Is Made
Semaglutide isn’t assembled purely in a chemistry lab. It starts in living cells. Novo Nordisk uses baker’s yeast (Saccharomyces cerevisiae) that has been genetically programmed to produce a precursor version of the semaglutide peptide. The yeast cells ferment and churn out this precursor, which is then extracted, purified, and chemically modified. During that modification step, the fatty acid chain is attached to the peptide backbone. A final step adds the first two amino acids to the chain, completing the semaglutide molecule.
This recombinant DNA manufacturing process is why Ozempic has been difficult for compounding pharmacies to replicate. The biological production and multi-step chemical modification require specialized equipment and quality controls.
Inactive Ingredients
The rest of the liquid in an Ozempic pen serves specific purposes: keeping the solution stable, sterile, and comfortable to inject. Each milliliter contains:
- Disodium phosphate dihydrate (1.42 mg): a buffering agent that keeps the solution at a pH of about 7.4, which matches your body’s natural pH and reduces stinging at the injection site.
- Propylene glycol (14 mg): a tonicity agent that balances the concentration of the solution so it doesn’t damage cells when injected.
- Phenol (5.5 mg): a preservative that prevents bacterial growth inside the pen, which is important because Ozempic pens are used over multiple weeks.
- Water for injections: the base solvent.
Small amounts of hydrochloric acid or sodium hydroxide may also be added during manufacturing to fine-tune the pH. That’s the complete list. There are no sugars, no gluten-containing compounds, and no insulin in the formulation.
Ozempic Is Not Insulin
Because Ozempic comes in a pen injector and is prescribed for type 2 diabetes, people sometimes assume it contains insulin. It does not. Semaglutide works through a completely different mechanism. Instead of directly lowering blood sugar the way insulin does, it mimics GLP-1 to stimulate your pancreas to release more of your own insulin when blood sugar rises after a meal. It also slows stomach emptying and reduces appetite by acting on hunger signals in the brain. The FDA label explicitly states that Ozempic is not a substitute for insulin and should not be used for type 1 diabetes.
If someone takes both Ozempic and insulin, they are administered as separate injections and should never be mixed in the same syringe.
Available Pen Strengths
Ozempic comes in three pen concentrations, each designed to deliver a specific dose per injection:
- 0.68 mg/mL pen: delivers either 0.25 mg or 0.5 mg per injection (used during the dose-escalation period and as a maintenance dose).
- 1.34 mg/mL pen: delivers 1 mg per injection.
- 2.68 mg/mL pen: delivers 2 mg per injection.
All three pens contain the same active and inactive ingredients. The only difference is the concentration of semaglutide per milliliter of solution. Each pen holds 3 mL of liquid total and is designed for a single patient over multiple weekly doses.