Use an approved site and the instructions for your device
The injection sites in the approved tirzepatide product instructions include the abdomen, thigh and upper arm. These are subcutaneous injections. The instructions do not designate a particular approved site as the one that guarantees more weight loss. Choose a permitted site you can use correctly, then rotate the site as directed.
A single-dose pen, multidose pen and vial with a separate syringe can have different preparation and injection steps. Read the instructions supplied with the actual device and have a clinician or pharmacist demonstrate them. An online video for another product may not apply.
Sources: Zepbound prescribing information · Mounjaro prescribing information
Rotation, skin condition and technique matter
Follow the device instructions on skin inspection, cleaning and where to place the needle or pen. Avoid injecting into irritated, damaged or otherwise unsuitable skin identified by the instructions. Rotation means changing the injection location as directed, not using a different unapproved route.
Do not inject into a vein or muscle. If you also use insulin, follow the product instructions for separate injection sites and do not mix semaglutide or tirzepatide with insulin in the same injection. Do not share a pen, even if the needle is changed. Upper-arm administration can require help depending on the device and your ability to reach the site.
Sources: Zepbound prescribing information · Mounjaro prescribing information
A compounded vial needs its own dose explanation
If a clinician prescribes a compounded vial, obtain the concentration and dose instructions from the dispensing pharmacy. A volume or syringe-unit number from another patient or an earlier vial may deliver the wrong milligram dose. FDA has received reports of serious dosing errors, including hospitalization.
Ask the pharmacist to show which syringe marking corresponds to the prescribed amount. If the label, prescription and instructions do not agree, do not improvise. Approved-brand injection directions are not a dose calculator for every compounded vial.
Sources: FDA’s Concerns with Unapproved GLP-1 Drugs Used for Weight Loss | FDA
Check storage and know when to ask for help
Inspect the supplied product and follow its instructions for storage and appearance. Do not use a product that fails the instructions’ checks. FDA advises against using injectable GLP-1 medicine that arrives warm or inadequately refrigerated; ask the pharmacy how to handle the shipment.
If a device appears to malfunction, medication spills or you are unsure the dose was delivered, contact the clinical team or pharmacist before taking more. A second dose can create an overdose. Severe or persistent symptoms need medical assessment. Trouble breathing or swallowing, swelling of the face, tongue or throat, or collapse may signal a serious allergic reaction: call 911 or the local emergency number immediately.
The useful question is which permitted site and technique you can use reliably for the actual prescription. Keep the instructions accessible and review them again when the device or concentration changes.
Sources: Zepbound prescribing information · Mounjaro prescribing information · FDA’s Concerns with Unapproved GLP-1 Drugs Used for Weight Loss | FDA · Anaphylaxis: MedlinePlus Medical Encyclopedia