Guides / Why does it sting, or leave a small welt?
Why does it sting, or leave a small welt?
2 min read
In short: A brief sting or a small bump that fades within hours is common. Cold liquid, wet alcohol on the skin, the preservative in bacteriostatic water and injecting too fast are the usual causes. Redness that spreads, heat, pus or fever needs a doctor.
Common, harmless causes
| Cause | Try |
|---|---|
| Liquid straight from the fridge | Let the filled syringe sit a few minutes first |
| Alcohol still wet on the skin | Let the swab area dry completely |
| Benzyl alcohol in bacteriostatic water | A mild sting is normal. Mention it to your pharmacist if it bothers you. |
| Injecting quickly | Push the plunger slowly and steadily |
| Reused or blunt needle | Use a new needle every time |
| Tense muscles | Relax the area. Pinch a fold of skin if you were shown to. |
Small bumps and redness
A small raised bump, or a little redness that fades within a few hours, is common, especially with larger volumes. A small bruise can happen if the needle nicks a tiny blood vessel. Rotate sites so the same spot isn't irritated over and over.
When to get help
See a doctor if you notice:
- Redness or swelling that grows over a day or more
- Warmth, pus or increasing pain at the site
- Fever or feeling unwell
- A lump that is hard, painful or doesn't go away
Call 000 straight away for swelling of the face, lips or throat, trouble breathing, or a widespread rash. These can be signs of a serious allergic reaction.
Keep reading
Injection sites and why rotation matters
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Why is my vial cloudy, or the powder loose?
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General information, not medical advice. Always follow your product's instructions and your healthcare professional.