Severe sunburn pain often leads people to seek immediate relief, frequently considering topical anesthetics like lidocaine. While effective for localized discomfort on intact skin, applying lidocaine to UV-damaged tissue introduces risks that outweigh temporary benefits. Sunburn fundamentally alters the skin’s structure, creating a pathway for the drug to enter the bloodstream at dangerous levels. This explains why using lidocaine on sunburn is generally advised against.
What Lidocaine Does to Nerves
Lidocaine is a local anesthetic that interrupts the transmission of pain signals. The feeling of pain relies on nerve cells generating an electrical impulse, known as an action potential, which travels to the brain. This impulse requires the movement of charged sodium ions across the nerve cell membrane through specialized channels.
The anesthetic works by physically binding to and blocking these voltage-gated sodium channels from the inside of the nerve cell. By preventing the inward flow of sodium ions, lidocaine effectively stabilizes the nerve membrane and inhibits depolarization. This blockage stops the nerve impulse from initiating or conducting, thereby eliminating the sensation of pain in the treated area. The numbing effect is temporary and lasts only as long as the drug remains concentrated around the nerve endings.
The Danger of Systemic Absorption on Burned Skin
The primary risk of applying topical lidocaine to sunburned skin stems from the loss of the skin’s natural barrier function. The epidermis, the outermost layer of skin, acts as a protective shield, limiting the absorption of substances into the body. However, ultraviolet radiation damage from a sunburn causes inflammation, cell death, and compromise of this barrier, essentially creating an open door for rapid drug absorption.
When lidocaine is applied to large areas of compromised skin, a much higher concentration of the drug crosses into the bloodstream (systemic absorption) than on healthy skin. The increased blood flow to the inflamed tissue, a characteristic of the inflammatory response, further accelerates this process. This rapid, uncontrolled systemic absorption can lead to a condition known as local anesthetic systemic toxicity.
Symptoms of this toxicity begin as effects on the central nervous system, including dizziness, confusion, slurred speech, and a metallic taste in the mouth. As blood levels rise, more serious effects can occur, such as muscle tremors, seizures, and eventual respiratory depression. The drug can also affect the cardiovascular system, potentially causing heart rhythm changes or a drop in blood pressure.
Furthermore, applying the anesthetic to damaged skin increases the potential for allergic sensitization or contact dermatitis. The broken barrier allows the drug to interact more readily with immune cells, triggering a delayed hypersensitivity reaction. This reaction can cause an irritating rash that worsens the burn symptoms.
Recommended Treatments for Sunburn Pain
Effective sunburn management focuses on cooling the skin and reducing the inflammatory response, rather than relying on topical anesthetics. Immediately applying cool compresses or taking a cool shower helps to draw heat away from the skin and ease the immediate discomfort. Gently pat the skin dry after washing, leaving a small amount of moisture behind.
Applying a soothing moisturizer that contains aloe vera or soy can help hydrate the skin and minimize the peeling process. These products are most effective when applied while the skin is still damp, helping to trap the water in the epidermis. Avoid thick, oil-based ointments, as they can trap heat and worsen the burn.
Over-the-counter non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen are recommended to manage pain and inflammation systemically. These medications inhibit the production of prostaglandins, compounds that mediate the pain, swelling, and redness associated with sunburn. Taking an NSAID as soon as the burn is noticed can lessen the overall severity of the inflammatory reaction.
Maintaining adequate hydration is important, as sunburn draws fluid to the skin’s surface, increasing the risk of dehydration. Drinking extra water helps to restore fluid balance and supports the body’s healing process. For localized inflammation or itching, a nonprescription 1% hydrocortisone cream can be used sparingly for a few days to reduce swelling and redness.