Yes, your feet can swell from a sunburn, a condition known as edema that signals a systemic reaction to the skin damage. A sunburn is an acute inflammatory response where ultraviolet (UV) radiation damages the DNA within skin cells. This cellular injury triggers biological events aimed at repairing the tissue, resulting in redness and swelling. Fluid retention in the feet and ankles is a direct consequence of this body-wide inflammatory process reacting to a severe burn.
The Inflammatory Response and Swelling
The swelling, or edema, is rooted in the body’s response to the radiation damage. When UV rays injure skin cells, the body releases chemical mediators like histamine and prostaglandins into the surrounding tissue. These substances increase blood flow to the burned area in a process called vasodilation. This increased blood flow causes the characteristic warmth and redness associated with a sunburn.
The chemical messengers also increase the permeability of the capillaries near the skin’s surface. This heightened permeability allows fluid, plasma proteins, and immune cells to leak out of the bloodstream and into the interstitial space. The accumulation of this leaked fluid causes the visible puffiness and tenderness. Fluid leakage typically begins within a few hours of sun exposure and can peak within 12 to 24 hours.
Why Lower Extremities Are Most Affected
While inflammatory fluid leakage can occur anywhere, swelling often becomes most noticeable in the feet and ankles. This concentration is explained by the principle of gravity and hydrostatic pressure. As fluid leaks from compromised capillaries, it is pulled downward toward the lowest points of the body.
This phenomenon is known as dependent edema, where gravity compounds fluid accumulation in the lower limbs. If a person spends time standing or sitting upright after a severe sunburn, hydrostatic pressure within the leg veins increases. This pressure makes it harder for the lymphatic system and veins to return fluid back toward the heart, causing the inflammatory fluid to pool in the feet and ankles.
Immediate Relief and Management Strategies
Managing swelling requires an approach focused on reducing inflammation and promoting fluid drainage. The most effective strategy is elevation, which directly counteracts the effects of gravity on the pooled fluid. Elevate your feet above the level of your heart for multiple periods throughout the day to encourage the lymphatic system to drain the fluid.
Applying cool compresses or taking a cool bath or shower can help constrict dilated blood vessels, slowing the rate of fluid leakage. Over-the-counter anti-inflammatory medications, such as ibuprofen, work systemically to inhibit the production of prostaglandins, mitigating the inflammatory response and reducing both pain and swelling. Staying well-hydrated is important because sunburn draws fluid to the skin’s surface, increasing the risk of systemic dehydration.
Recognizing Signs of Severe Reaction
While mild edema is common after a severe sunburn, certain symptoms indicate a systemic reaction requiring immediate medical attention. If swelling is accompanied by a fever higher than 102 degrees Fahrenheit, chills, or widespread blistering, seek professional care. These signs indicate the body’s reaction has progressed beyond a localized burn.
Signs of severe dehydration or systemic illness also warrant medical evaluation, including dizziness, confusion, nausea, or vomiting. Watch for signs of infection in the swollen area, such as increasing pain, red streaks spreading away from the burn, or pus. A doctor may need to administer intravenous fluids or prescription-strength anti-inflammatory treatments to manage serious complications.