Overview
Blister beetles release cantharidin when crushed against skin.
Blisters appear hours later and heal in about a week.
Symptoms
Common signs:
- Blister after beetle contact
Less common
- Itching
Look up a symptom: Blisters · Red spot, bump, or patch on the skin
When to get medical care
Call 911This isn't an emergency by itself. Call 911 for trouble breathing, chest pain, or fainting.
Get care todayEye contact.
See a doctor soonSymptoms that last or keep coming back.
Causes
Cantharidin.
Diagnosis
A clinician asks about your symptoms and may order tests.
The exam
A physical exam.
Treatment
Treatment depends on the cause and how severe it is.
Self-care
- Wash with soap
- Don't pop blisters
- Wash skin right away after touching a beetle
- Wash with soap and water
Prevention
To lower your risk or prevent problems:
- Brush beetles off rather than crushing them
Which doctor treats this
- Urgent care or the ER can treat it first. For minor problems, your primary care provider can help.
- Large or deep burns are best treated at a burn center.
Back to school, work, or sports
- Most people can go to school or work. Keep the wound clean and covered.
- Avoid pools and hot tubs until the skin heals.
Children, pregnancy, and older adults
- Gardeners and farm workers: Most exposed.
- Farm workers: Higher risk.
Outlook
Heals without scarring.
Getting ready for your visit
Bring a list of your symptoms and medicines.
What to bring
- A list of your medicines and supplements
- Notes on when symptoms started and what makes them better or worse
Questions to ask
- What's causing this?
- What treatment do you recommend?
- Is this blister infected?
Research studies
Research studies test new ways to find and treat health problems. Some are looking for volunteers. Talk with your doctor before joining one.
Search ClinicalTrials.gov for studies on Blister beetle burns
Sources
Last updated 2026-11-12.