A practical rotation system for weekly GLP-1 injections across the abdomen, thigh and upper arm — why rotation matters and how to keep track of it.

Why rotation matters

GLP-1 medications are injected subcutaneously — into the fat layer just under the skin, not into muscle. Injecting into the same spot week after week can cause the tissue there to thicken or harden, a change clinicians call lipohypertrophy. Beyond being uncomfortable, hardened tissue absorbs medication less predictably, which means the same dose may not behave the same way.

Rotation is the simple fix. It costs nothing, takes no extra time, and the only hard part is remembering where the last few shots went.

The three site families

Abdomen. The most commonly used area, and generally the easiest to reach yourself. Stay at least 5 cm (about two inches) away from your navel in every direction.

Thigh. The front and outer surface of the upper leg, roughly the middle third between hip and knee. Avoid the inner thigh.

Upper arm. The back of the arm, in the fatty area between shoulder and elbow. This one is difficult to do one-handed, so it tends to be the site people use when someone else is administering the shot.

Areas to avoid

Skip anywhere that is bruised, scarred, red, swollen or tender. Skip moles and skin conditions. If an area feels firm or lumpy compared to the skin around it, leave it alone entirely and mention it at your next appointment.

A rotation that works

The easiest system is to move site family every week on a fixed cycle — abdomen, thigh, arm, then back to the start — and to shift a few centimetres within the family each time you return to it. Some people prefer to split each site into quadrants and work around them.

The specific pattern matters much less than having one at all. What breaks rotation is not a bad system; it is choosing in the moment, week after week, and quietly favouring the spot that is easiest to reach.

Keeping track

By week six, nobody reliably remembers where week three went. This is the part worth writing down, whether that is a note on your phone, a printed body chart on the fridge, or an app that suggests the next site for you.

Log the site at the moment you inject, not later. A record you fill in from memory the next day is the record that quietly drifts.

Talk to your provider about

Any area that has become firm, lumpy or numb
A site that consistently stings, bruises or bleeds more than the others
Whether your specific medication and pen have site guidance of their own