Sunburn Blister vs. Cold Sore: How to Tell the Difference (With Pictures)

If you’ve ever had a blister pop up on your lip, you know how stressful it can be. Not only are they painful, but it can be hard to know what’s causing them. You may begin to wonder if a lip blister is a sunburn blister or a cold sore. Both of these conditions cause painful blisters, but there are some key differences to help you tell them apart.

Here, we’ll review what causes sunburn blisters and cold sores, what they look like (with pictures), and what you can do about them.

What is a sunburn blister?

Sunburn blisters are fluid-filled bumps on the skin that are caused by a severe sunburn. They usually appear a few hours or more after getting a sunburn.

Sunburn blisters occur when the skin is exposed to too much ultraviolet (UV) radiation. This damages the connection between the top two layers of skin, causing a fluid-filled blister to form.

What do sunburn blisters look like?

Sunburn blisters form on skin that has developed a sunburn. The pink or red discoloration caused by sunburn is easy to identify in fairer skin, but it may be more subtle in darker skin tones. The blisters that can form are usually filled with clear or yellowish fluid. They can be small or merge together, forming larger blisters. 

Sunburn blisters can happen on any area of skin that has been exposed to the sun. Common locations include:

• Face, including the lips and nose

• Shoulders

• Chest

• Upper back

• Back of the neck

• Tops of the feet

Pictures of sunburn blisters

Here are some pictures of sunburn and sunburn blisters.

Sunburn blisters form on the shoulder.

A person’s skin starts to peel after having a sunburn on the face.

What is a cold sore?

A cold sore (also called a fever blister) is a painful blister caused by the herpes simplex virus (HSV). It’s usually transmitted through person-to-person contact (like kissing) or through sharing contaminated objects (like a glass). Once a person develops a cold sore, the virus stays inside the body and a cold sore can develop again in the same location.

What does a cold sore look like?

Cold sores usually develop on or around the lips, but they can also appear around the nose, inside the mouth, or on the chin. Cold sores can go through four different stages:

1. They usually begin with a tingling or burning sensation.

2. Then, small, fluid-filled, pink or yellow blisters form. The blisters usually develop in clusters, and the surrounding skin can be red, violet, or brown.  

3. The blisters then burst open and leave open sores that can ooze a yellow fluid.

4. Finally, the sores form crusts and scabs as they start to heal and dry out.

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• Treating a sunburn: From cold compresses to pain relievers, learn the best way to get fast relief from a sunburn.

Pictures of cold sores

Here are some pictures to help show what cold sores look like.

A cold sore forms on the upper lip.

A cold sore forms on the tongue.

Sunburn blisters vs. cold sores

Here’s a chart that shows some of the main differences between sunburn blisters and cold sores. 

Treatment for sunburn blisters and cold sores

Sunburn blisters and cold sores have different treatments. Here’s an overview of what to do for each.

Sunburn blisters treatment

If you get a sunburn with blisters, start by cooling the area with cold compresses or a cool shower. Here are some other steps to take that can help reduce symptoms:

• Use aloe vera to soothe the area.

• Avoid dehydration by drinking plenty of fluids.

• Take over-the-counter (OTC) pain relievers if needed.

• Avoid popping or picking at the blisters.

• Keep the area out of the sun until it heals.

• Cover blisters with a nonstick bandage if they break open.

If sunburn blisters cover a large area of your body or you’re having fever, chills, or dizziness, you should get medical attention.

Cold sore treatment

The best way to get rid of cold sores is with antiviral creams (like Abreva) or prescription medications such as valacyclovir (Valtrex). Some other treatments that may help include:

• OTC pain relievers

• Lysine supplements

• Cold compress to reduce pain and swelling

• Numbing medication (like Orajel)

How to prevent sunburn blisters and cold sores

The best way to prevent sunburn blisters is to protect your skin from the sun. There are some ways to keep your skin safe when exposed to the sun, such as:

• Wear sunscreen that has SPF 30 or more.

• Wear sun-protective clothing like hats and sleeves.

• Seek shade and avoid strong midday sun. 

Sun protection is also an important way to prevent cold cores. This is because sun exposure is a common trigger for cold sores. In addition to using lip balm with SPF, some other ways to prevent cold sores include:

• Taking preventive antiviral medications (if prescribed)

• Minimizing stress

• Keeping lips moisturized to reduce cracking or chapping

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Written by:

Maria Robinson, MD, MBA

Maria Robinson, MD, MBA, is a board-certified dermatologist and dermatopathologist who has practiced dermatology and dermatopathology for over 10 years across private practice, academic, and telehealth settings. She is a fellow of the American Academy of Dermatology and the American Society of Dermatopathology.

Edited by:

Karla Robinson, MD

Karla Robinson, MD, is a medical editor for GoodRx. She is a licensed, board-certified family physician with almost 20 years of experience in health through varied clinical, administrative, and educational roles.

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Images used with permission from VisualDx (www.visualdx.com).