Scars, moles, tattoos, stretch marks, bruises and broken skin. Which patches to pass over when you pick a site, and what to use instead.
Key points
- 01Scars and any hardened patch. Published injection-technique recommendations describe avoiding thickened, scarred or hardened tissue, because absorption through it is unpredictable. This is the one entry on the list with a firm evidence base, and it is why the standing instruction is to feel the site with your fingertips before the needle goes anywhere near it.
- 02Moles, skin tags and raised marks. Nothing about a mole makes it a target, and two things make it worth a wide berth: you cannot see the tissue you are entering, and a mole you keep injecting around is a mole you stop watching for change. Leave a couple of centimetres of ordinary skin between the mark and the needle.
- 03Tattoos, and healing tattoos especially. A fresh or healing tattoo is broken skin and is out until it has healed completely. Settled ink is ordinary skin underneath, but it hides redness, and redness is exactly the change you would want to notice at a site. Where you have a choice, choose un-inked skin so the site stays readable.
- 04Stretch marks, for a practical reason. No guidance forbids injecting through a stretch mark. The reason to route around them is that the tissue there is thinner and less uniform than the skin beside it, and they tend to sit right across the lower abdomen where many people inject. Aim for the intact skin between them rather than the mark itself.
- 05Broken, inflamed or infected skin. An eczema flare, sunburn, a rash, a scratch, a spot that is already red and warm: all of it waits until the skin has healed. Putting a needle through inflamed skin hurts more and gives bacteria a route inward, and our post on infection red flags describes what that route can turn into.
- 06Yesterday's site, a live bruise and the navel margin. Keep roughly a finger's width from the last few punctures, skip a bruise until the colour has gone, stay about two inches clear of the navel, and avoid the line where a waistband sits and rubs all day. None of these are dramatic risks; together they are most of what people mean by a bad site.
Frequently asked questions
Can I inject into a tattoo?+
A healing tattoo is broken skin and is out until healed. Settled ink is ordinary skin, but it masks redness at the site, so choose un-inked skin where you have the option. Educational information only, not medical advice.
How far away from a mole or a scar should I stay?+
Far enough to be injecting plainly normal skin, which for most people means a couple of centimetres. Published guidance is specific about avoiding scarred and hardened tissue because absorption through it is unpredictable.
Do stretch marks matter?+
No rule forbids them. The tissue is thinner and less even than the skin around it, and they often cross the exact area people use, so the practical move is to aim between them rather than through one.
Can I use a spot that is still bruised?+
Wait until the colour has faded. A bruise is blood already sitting in the tissue, injecting into it is more uncomfortable, and it makes any new mark impossible to interpret.