Causes of Sunburn
Sunburn is caused by overexposure to ultraviolet (UV) radiation, which comes primarily from the sun or artificial sources like tanning beds. There are two main types of UV rays that reach the earth: ultraviolet A (UVA) and ultraviolet B (UVB). UVB rays are the primary cause of sunburn, while UVA rays penetrate deeper into the skin and are more associated with aging. When UV rays hit the skin, they damage the DNA within skin cells. To prevent these cells from becoming cancerous, the body triggers an immune response that leads to programmed cell death and inflammation. This inflammation causes the blood vessels to dilate, resulting in the redness, heat, and pain associated with a burn. The body produces melanin, a pigment that darkens the skin, as a defense mechanism to block UV rays, but when exposure exceeds the protective capacity of melanin, a burn occurs.

Risk Factors and Triggers
Certain factors make individuals more susceptible to burning. People with fair skin, light hair, and blue or green eyes generally have less melanin and burn more easily. However, people with darker skin can also get sunburned. Environmental factors play a major role; UV rays are strongest between 10 a.m. and 4 p.m., at higher altitudes, and closer to the equator. Reflective surfaces like snow, water, and sand can intensify UV exposure. Certain medications, including specific antibiotics, retinoids, and diuretics, can induce photosensitivity, making the skin burn much faster than usual. Wet skin may also burn more easily than dry skin.

Prevention Strategies
The most effective way to prevent sunburn is to avoid direct sun exposure during peak intensity hours and to seek shade whenever possible. Wearing protective clothing, such as wide-brimmed hats, sunglasses, and tightly woven long-sleeved shirts, provides a physical barrier against radiation. Broad-spectrum water-resistant sunscreen with an SPF of 30 or higher should be applied generously to all exposed skin 15 to 30 minutes before going outside and reapplied every two hours or after swimming or sweating. Avoiding tanning beds is essential for prevention. While these steps prevent the acute burn, they also reduce the risk of long-term damage such as premature aging and skin cancer.

Signs and Symptoms
The symptoms of sunburn typically do not appear immediately but develop a few hours after exposure. The first sign is usually the skin turning pink or red, a condition known as erythema, which is more difficult to see on darker skin tones. The affected area often feels hot to the touch and becomes painful or tender. Swelling may occur in moderate cases. In severe cases, fluid-filled blisters may form on the skin surface, indicating deep tissue damage. As the skin heals, typically several days later, the damaged top layer may peel away. Severe sunburn, sometimes called sun poisoning, can cause systemic symptoms affecting the whole body.

• Fever and chills
• Nausea or vomiting
• Headache and fatigue
• Dizziness or confusion

Diagnosis
Healthcare providers usually diagnose sunburn based on a visual examination of the skin and a history of recent sun exposure. No specific laboratory tests or imaging are generally required for a standard diagnosis. The doctor will assess the extent of the burn, the presence of blisters, and signs of infection. If systemic symptoms are present, the provider may check vital signs like blood pressure and temperature to rule out heat exhaustion or heatstroke.

Differential Diagnosis
While the cause is usually obvious, clinicians may consider other conditions if the reaction is unexpected or severe. Photosensitivity reactions caused by medications or topical products (phytophotodermatitis) can mimic severe sunburn but may result in different blistering patterns or hyperpigmentation. Heat rash, allergic reactions to sunscreen ingredients, or other forms of dermatitis might also be considered if the presentation is atypical.

Home Remedies and Self-Care
Treatment for mild to moderate sunburn focuses on relieving symptoms while the skin heals itself. Cooling the skin is the first priority; this can be done with cool baths, showers, or damp compresses. It is important to avoid harsh soaps that irritate the skin. Applying a gentle moisturizer, particularly those containing aloe vera or soy, can help soothe the skin and reduce dryness. Over-the-counter pain relievers such as ibuprofen or aspirin can help reduce pain and inflammation, especially if taken soon after sun exposure. Drinking plenty of water is crucial to prevent dehydration, as the burn draws fluid away from the rest of the body to the skin surface. Avoid using oil-based products like petroleum jelly or butter on a fresh burn, as these can trap heat and worsen the condition. Do not pop blisters, as they protect the underlying skin from infection.

Medical Treatment
For severe burns, medical intervention may be necessary. A doctor might prescribe stronger prescription creams to reduce inflammation, such as potent corticosteroids. If the sunburn is accompanied by severe dehydration or heatstroke, intravenous (IV) fluids may be administered in a hospital setting. If blisters break and become infected, antibiotics may be prescribed to treat the infection. Treatment does not reverse the DNA damage caused by UV radiation but helps manage the acute symptoms and complications.

When to Seek Medical Care
While most sunburns can be managed at home, certain situations require professional medical attention. You should consult a healthcare provider if the sunburn covers a large portion of the body or if blisters form on the face, hands, or genitals. Immediate emergency care is needed if signs of sun poisoning or heat illness appear.

• High fever (over 103°F or 39.4°C) with chills
• Extreme pain or confusion
• Signs of infection in blisters, such as pus or red streaks
• Severe dehydration symptoms like lack of urine output or fainting

Severity Levels
Sunburn severity ranges from mild to severe based on the depth of the burn and the amount of body surface area affected. Mild sunburns typically involve only redness and tenderness (first-degree burns). Moderate sunburns are more painful, involve swelling, and may cause the skin to feel hot. Severe sunburns can result in blistering (second-degree burns) and may be accompanied by systemic illness. The severity is influenced by skin type, the intensity of the UV radiation, and the duration of exposure.

Duration and Course
The symptoms of sunburn follow a specific timeline. Redness typically appears 2 to 6 hours after exposure and peaks within 12 to 24 hours. The pain and inflammation usually subside after 48 to 72 hours. Mild burns generally heal within 3 to 5 days, while moderate burns may take a week or longer. Peeling usually begins a few days after the burn appears and can last for several days as the body sheds the damaged skin cells. The pigmentation changes, such as tanning or dark spots, may persist for weeks or months.

Complications and Long-Term Effects
Short-term complications include infection if blisters are broken and dehydration. The most significant concern regarding sunburn is the long-term impact on health. Repeated exposure and sunburns accelerate the skin's aging process, leading to photoaging, which is characterized by deep wrinkles, dry, rough skin, and liver spots. More critically, sunburns significantly increase the risk of developing skin cancer, including basal cell carcinoma, squamous cell carcinoma, and melanoma. Melanoma is the most dangerous form of skin cancer, and severe blistering sunburns during childhood or adolescence are strong risk factors for its development later in life.

Impact on Daily Activities
During the acute phase, sunburn can significantly interfere with daily life due to pain and discomfort. Movement may be restricted if the burn affects areas like the back, shoulders, or legs, making it difficult to wear regular clothing, sleep comfortably, or perform physical tasks. Friction from sheets or clothes can exacerbate the pain. Individuals may need to stay indoors and avoid further sun exposure completely until the burn heals, which can limit participation in social or outdoor events. The unsightly appearance of peeling skin during the healing phase can also cause temporary self-consciousness.

Questions to Ask Your Healthcare Provider
When visiting a doctor for severe sunburn or for a skin checkup following a history of burns, asking specific questions can help you manage your health and risks effectively.

• What is the best way to treat my blisters without causing an infection?
• Are any of the medications I am currently taking making me more sensitive to the sun?
• What specific signs of infection should I look out for as my skin heals?
• Given my history of sunburns, how often should I be screened for skin cancer?
• What SPF level and type of sunscreen do you recommend for my skin type?

Q: Does getting a "base tan" protect me from sunburn?
A: No, a base tan provides very minimal protection, equivalent to an SPF of only about 3 or 4. A tan is actually evidence that the skin has already been damaged by UV radiation and is trying to protect itself, so relying on a base tan can lead to a false sense of security and further damage.

Q: Can I get sunburned on a cloudy or cool day?
A: Yes, up to 80 percent of the sun's UV rays can penetrate through clouds. You can also get burned on cool days because the heat of the sun is not what burns you; it is the invisible UV radiation, which is present even when temperatures are low.

Q: Is it safe to use leftover sunscreen from last year?
A: Sunscreen typically has a shelf life of three years, but if it has been exposed to high heat (like in a hot car) or looks and smells different, it may have lost its effectiveness. It is safer to purchase a new bottle if you are unsure or if the expiration date has passed.

Q: Does peeling skin mean the sunburn is healing?
A: Yes, peeling is the body's way of shedding dead and damaged skin cells to make way for new skin. It is a sign that the healing process is underway, but you should allow the skin to peel naturally and avoid pulling it off to prevent infection and scarring.

Q: Are people with dark skin immune to sunburn?
A: No, while people with more melanin have some natural protection against UV rays, they can still suffer from sunburn and skin damage. Although the redness may be harder to see, the skin can still feel hot, painful, and suffer DNA damage that leads to skin cancer.