How to actually
give the injection.

Wegovy, Ozempic, Zepbound, and Mounjaro all ship as pre-filled or pre-loaded pens. The dose is measured at the factory, so there's no math for you to do, only a mechanical sequence to get right. That sequence differs slightly by brand, some pens need priming before the first use, some dial to a dose, some are single-use with nothing to set, so this is the general shape, not a replacement for your specific pen's instructions for use.

If you see a drop of liquid on your skin or the pen tip after removing it, that's usually normal and doesn't mean you missed the full dose, but if you're ever unsure whether a dose actually went in, call your provider rather than guessing and re-dosing.

This is where the extra steps live. Before you draw anything, you should already know your vial's concentration and your target dose, see Know Your Number if you haven't nailed that part down yet, because everything below assumes you already know exactly how much to draw.

Semaglutide and tirzepatide are both injected into the fatty layer just under the skin, not into muscle. Three general areas work: the abdomen, the front of the thigh, and the back of the upper arm.

Rotate between these areas, and between spots within each one, rather than returning to the exact same point every week. A simple way to keep track on the abdomen: picture it as a clock face with your navel at the center, and move to a different hour each injection, working your way around. Space each new site roughly two finger-widths from the last one.

Skip any spot that's bruised, scarred, hard, or irritated, and never inject into the same tiny patch repeatedly. Repeated injections in one small area can cause lipohypertrophy, a firm lump under the skin that can also make the medication absorb less predictably, which is a separate problem from the injection itself going wrong.

Unopened branded pens and ready-to-use vials generally belong in the refrigerator, and shouldn't be frozen, if one freezes, don't use it, even if it looks fine afterward. Once you've started using one, most brands allow a room-temperature window before it needs to be discarded, but that window is genuinely different by product, commonly somewhere in the three-to-four-week range, so this is exactly the kind of detail to confirm on your own product's instructions for use rather than assume matches someone else's.

If you're working with a compounded peptide that ships as a lyophilized powder, the freezer is exactly where it belongs until you mix it with bacteriostatic water or whatever your provider specifies. Once it's reconstituted into a liquid, that changes, it moves to the refrigerator and stays there, and it should never go back into the freezer. Freezing a liquid solution risks damaging the peptide itself, which a freeze-dried powder isn't exposed to in the same way.

Keep everything away from direct light and heat regardless of which state it's in, and don't move a ready-to-use product back and forth between the fridge and room temperature, that back-and-forth isn't what the stability data is based on. If a liquid ever looks cloudy, discolored, or has particles floating in it, don't use it, regardless of how much time is left on the clock.

Pick a consistent day and rough time each week, and build your rotation pattern into that same routine rather than deciding fresh every time. Keep a sharps container on hand from day one, not just when you remember to buy one, and never drop a used needle straight into household trash or a recycling bin. When it's full, most pharmacies and some municipal programs will take it back for proper disposal.

If something feels genuinely off, unusual pain, a site that looks infected instead of just irritated, or you're simply not confident the dose actually went in, call your provider rather than guessing. That call is what they're there for.