GLP-1s and Stretch Marks: Two Different Questions

Two questions, not one

Women ask about GLP-1s and stretch marks in two ways.

The first is whether the medicine causes them. The second is where to put the needle when your stomach is covered in them.

They have different answers. Here is each one.

Does the medicine cause stretch marks?

Almost certainly not.

Stretch marks come from skin being stretched. A review of the research describes them as thinned skin with changed tissue underneath. Hormones, mechanical stress and family history are all linked to them¹.

Losing weight is the opposite. Your skin is not being stretched. It has less underneath it.

What does happen is that marks you already have become easier to see. The fat under them shrinks. Marks that used to sit flat and smooth now show more texture.

The medicine did not draw them. It removed what was holding them tight.

One exception is worth naming. New marks can appear during rapid weight gain, including a regain after stopping treatment. That is the direction of the change, not the drug.

Can you inject into a stretch mark?

Here is the honest answer: nobody has studied this.

There is no research on injecting a GLP-1 into a stretch mark. No absorption data exists. Anyone giving you a percentage made it up.

What we can do is reason from anatomy, and say clearly that it is reasoning.

A stretch mark is a change in the skin. The injection goes into the fat under the skin. So the tissue that changed is not the tissue receiving the medicine. That suggests the marks do not matter much.

The label helps here too. It lists three places to inject: the abdomen, the thigh and the upper arm. It also reports that the medicine reached similar levels in all three². Where you inject is not a dose decision.

What to avoid instead

This is the part that actually matters, and it is not stretch marks.

Stay a few centimeters away from a cesarean scar. Surgical scar tissue is dense and its blood supply is disrupted. That is a real reason to expect uneven absorption.

Do not use the same small spot every week. This is the mistake most people make. You find a place that does not sting and you keep going back. Over time that tissue thickens and absorbs less predictably.

The label already tells you the fix: rotate sites with each dose.

If it is how they look

For many women this question is not really about medicine. It is about seeing an old mark become more visible at the moment you expected to feel better.

The research on treating stretch marks is disappointing, and it is fairer to say so. The same review concludes that despite many options, no single treatment has been proven effective¹.

Two things are still true. Newer red or purple marks respond better than old white ones. And marks fade slowly on their own over years, which is what most before-and-after photos are showing.

The short version

The medicine is not making new marks. Losing the volume under them is making the old ones easier to see.

Injecting into one has never been studied, and the anatomy suggests it is fine. Rotate your sites, keep clear of a surgical scar, and remember you have two other approved places to inject.