Skin Health More Skin Conditions Causes, Diagnosis, and Treatment of Vesicles By Heather L. Brannon, MD Heather L. Brannon, MD, is a family practice physician in Mauldin, South Carolina. She has been in practice for over 20 years. Learn about our editorial process Heather L. Brannon, MD Medically reviewed by Medically reviewed by Casey Gallagher, MD on April 07, 2020 Casey Gallagher, MD, is board-certified in dermatology. He is a clinical professor at the University of Colorado in Denver, and co-founder and practicing dermatologist at the Boulder Valley Center for Dermatology in Colorado. His research has been published in the New England Journal of Medicine. Learn about our Medical Review Board Casey Gallagher, MD on April 07, 2020 Print A vesicle, also known as a blister or a vesicular lesion, forms when fluid becomes trapped under the epidermis, creating a bubble-like sac. The surrounding skin keeps fluid in place, but the vesicle can break open very easily and release the fluid. This photo contains content that some people may find graphic or disturbing. See Photo Joanne Green / Getty Images Vesicles are defined as less than one centimeter in diameter, and they can contain fluid or air. They can be signs of chicken pox, early stages of eczema, contact dermatitis, shingles, and herpes simplex. Causes Vesicles are triggered by a number of causes. Some are considered minor, like friction. If you've ever broken in a new pair of shoes or used your hands playing sports or doing manual labor, you've probably dealt with blisters. Other minor causes include allergic reactions, contact dermatitis, exposure to chemicals, cold sores, burns, and eczema. If you have persistent, large legions that multiply or change shape or color, see your doctor. Some causes are serious and require a visit to the doctor if the vesicles are a result of an existing condition, including: Autoimmune disorders Chickenpox or shingles Herpes Impetigo Appearance A typical vesicle looks like a little bubble of fluid under the skin. The larger the vesicle, the more prone to breaking open, which can be quite painful. It can also cause inflammation in the surrounding area. If a blister bursts prematurely before the underlying skin heals, it poses a greater risk of infection. Blisters that are larger than one centimeter are technically called bullae (bulla is the singular). Diagnosis Vesicles are easy to recognize since they appear on the surface of the skin. In many cases, your recent health history and/or conditions you have is enough information for a doctor to give a diagnosis on the spot. However, if the cause is uncertain, a doctor might take a fluid sample or arrange a biopsy of skin tissue. Treatment As tempting as it might be, do not pick or scratch at any lesions. It's important to keep the area clean and the vesicle sealed so the skin beneath can heal. If a vesicle is swollen and painful, a doctor can drain the fluid in a sterile manner, allowing the skin to heal effectively without risking infection. Vesicle treatment depends on the cause. In many cases, vesicles are treated with over-the-counter medication, or they could heal on their own. Serious cases often come with more serious symptoms, like inflammation or infection, and medication is prescribed accordingly. Vesicles caused by autoimmune disorders can be treated with an antibiotic to combat infection and a corticosteroid to reduce inflammation. Prevention Vesicles aren't always preventable. Those caused by genetics or a viral infection could appear again in the future. Proper care can treat vesicles as they appear, but if they're brought on by a serious condition, they're likely going to return. If your allergies trigger vesicles, avoid your known allergens, and do not share things like straws, cups and lip care products with others. Was this page helpful? Thanks for your feedback! Sign up for our Health Tip of the Day newsletter, and receive daily tips that will help you live your healthiest life. Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit Article Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Cedars-Sinai. Blisters.