Short answer: Using a weight-loss injection pen involves these steps: let the pen warm up briefly if its leaflet suggests it, attach a new needle, set the dose dial, insert the needle into the skin at 90 degrees and press the button, then keep the needle in for the time your pen's instructions give so the full dose is delivered (on Ozempic and Wegovy FlexTouch pens, count slowly to 6 after the dose counter shows 0).

Key takeaways

  • If your pen's leaflet suggests it, a pen taken out of the refrigerator can be left out briefly before injecting.
  • Always attach a new, sterile needle for every injection.
  • On Ozempic and Wegovy FlexTouch pens, keep the needle in after the dose counter shows 0 and count slowly to 6; for other pens, follow the pen's instructions for use.
  • Do not press on or rub the injection site; if there is bleeding, press gently with a cotton ball.

GLP-1 medications are mostly given with prefilled pens. The type of pen varies by product: some are single-use and need no dose setting, while others are multi-dose and you select the dose for each injection. The steps below describe the shared flow; the package leaflet for your own pen is what counts.

It is recommended that you do your first injection with your doctor or a healthcare professional. This page does not replace that training.

Before the injection

  • Wash your hands.
  • If your pen's leaflet suggests it, take the pen out of the refrigerator and let it sit briefly before injecting.
  • Check the medication name, dose and expiration date on the label.
  • Look at the liquid: it should be clear and colorless. Do not use it if it is cloudy or has particles.
  • Choose the injection site, knowing which site is up this week.

Step-by-step injection

  • Remove the pen cap.
  • Attach a new, sterile needle; a new needle is used for every injection.
  • If your pen requires a flow check (priming), do it as the instructions say. Most single-use pens do not require this.
  • On multi-dose pens, turn the dose selector to the dose your doctor set.
  • Insert the needle straight into the skin and hold the button down.
  • Keep the needle in for the time stated in your pen's instructions (on Ozempic and Wegovy FlexTouch pens, count slowly to 6 after the dose counter shows 0). Pulling out early leaves part of the dose outside.
  • Withdraw the needle from the skin and do not rub the site.
  • Take the needle off the pen and throw it in a sharps disposal container; put the pen cap back on.

Pen or vial?

Some treatments are given with a vial and syringe. In that case, the dose is read from the unit markings on the syringe, and your doctor determines the calculation. The injection technique is similar; the difference is that you draw up the dose instead of the pen. Do not calculate syringe units on your own.

Common mistakes

  • Pressing the button and pulling out right away: the full dose is not delivered.
  • Reusing the same needle; a dull needle increases both pain and tissue damage.
  • Injecting a cold pen straight from the refrigerator when its leaflet says to let it warm up first.
  • Injecting into the same spot every week.
  • Throwing used needles in the regular trash.

Logging the injection

Haftra logs an injection with a single tap, keeping the site, dose and time together. At the next injection, it reminds you of the next site. It does not suggest doses and does not calculate syringe units. It is free and can be used without an account.

iPhone, iPad and Apple Watch. Free.

Frequently asked questions

How do you use a weight-loss injection pen?

Wash your hands, let the pen sit briefly out of the refrigerator if its leaflet suggests it, attach a new needle, insert the needle straight into the skin and hold the button down. Keep the needle in for the time stated in your pen's instructions, then withdraw it and do not rub the site.

Is the needle changed every time?

Yes. A new, sterile needle is used for every injection. Reusing the same needle is not safe: the tip gets dull, it can clog, and it increases pain, tissue damage and the risk of infection.

Can I use the pen right after taking it out of the refrigerator?

Follow your pen's leaflet. If it suggests letting a cold pen sit out briefly before injecting, do that; the leaflet also says how long the pen can be kept out of the refrigerator.

Can I pull the needle out right after pressing the button?

No. Keep the needle in the skin while holding the button down for the time stated in your pen's instructions. On Ozempic and Wegovy FlexTouch pens, that means counting slowly to 6 after the dose counter shows 0. Pulling out early lets part of the dose leak back out.

Will I feel pain during the injection?

The needles are very thin, and most people feel little pain.

Sources

  • EMA - Mounjaro (tirzepatide)
  • EMA - Ozempic (semaglutide)
  • EMA - Wegovy (semaglutide)
  • NHS - Obesity treatment
  • U.S. Food and Drug Administration (FDA)

Last reviewed: August 4, 2026