A cool bath with the right additions can significantly ease sunburn pain, reduce inflammation, and help your skin start healing. The best options are colloidal oatmeal, baking soda, milk, and Epsom salt, each working through different mechanisms. Keep the water cool (not cold), soak for about 10 minutes, and moisturize immediately after.
Colloidal Oatmeal
Colloidal oatmeal is one of the most effective bath additions for sunburned skin. It contains natural polyphenols called avenanthramides that block inflammatory signals in the skin, and it also reduces the release of compounds that trigger redness and swelling. You can buy colloidal oatmeal packets at most drugstores, or make your own by grinding plain, unflavored oats in a blender until they form a fine powder that dissolves in water. Add one to two cups to a full bathtub and swirl until the water turns milky.
The oatmeal creates a protective film on the skin’s surface that locks in moisture and soothes itching. This is especially useful in the days after a sunburn when peeling starts and the skin feels tight and dry. If the oatmeal settles to the bottom of the tub, stir it occasionally as you soak.
Baking Soda
Baking soda is a simple, inexpensive option. The Mayo Clinic recommends adding about 2 ounces (60 grams), roughly a quarter cup, to a full bathtub. It creates a mildly alkaline solution that helps calm irritation and reduce the stinging sensation of sunburned skin. Baking soda works well for mild to moderate sunburns where the skin is red and hot but not blistered.
Milk
Adding one to two cups of whole milk to your bath provides a combination of fat and protein that your skin absorbs directly. The milk fats seep into the outer layer of skin and add hydration, which sunburned skin desperately needs since UV damage disrupts the skin’s ability to retain moisture. Whole milk works better than skim because the higher fat content delivers more of that moisturizing benefit. You want just enough to make the water slightly cloudy.
Epsom Salt
Dissolving one cup of Epsom salt (magnesium sulfate) in a full bath can help reduce swelling and ease pain from more intense sunburns. Magnesium has anti-inflammatory properties, and the salt solution can draw some of the heat and fluid buildup out of inflamed tissue. This option is particularly useful if you’re dealing with puffiness or hives alongside the burn.
Vinegar as a Compress Instead
Vinegar is sometimes recommended for sunburn, but it works better as a targeted compress than a bath additive. A dermatologist at UNC Health recommends mixing 1 tablespoon of white vinegar per cup of water, soaking a washcloth in the solution, and applying it directly to the burned area. The vinegar acts as a mild antiseptic and helps gently loosen dead skin. This approach is especially useful if your sunburn has blistering, since it helps guard against infection while easing pain.
What to Avoid Adding
Essential oils are the biggest thing to skip. Despite claims that peppermint, eucalyptus, or lavender oil can calm inflamed skin, dermatologists warn that essential oils routinely cause contact dermatitis, and this risk is higher on sunburned or broken skin. Peppermint oil in particular has been shown to cause skin irritation and redness even on healthy skin. Applying a fragrant oil to a sunburn risks layering a chemical irritation on top of the existing damage, essentially giving yourself a chemical burn on top of a sunburn. If your skin has any blisters, open sores, or is very red and painful, essential oils can cause a serious allergic reaction.
Also avoid bubble bath, scented bath products, and anything containing dyes or alcohol. These will strip moisture from already compromised skin and intensify the burning sensation.
Water Temperature and Timing
Use cool water, not cold. Water that’s too cold can cause the blood vessels in your skin to constrict, which traps heat in the deeper tissue rather than letting it dissipate. Lukewarm to cool is the sweet spot. You want it to feel soothing when you step in, not shocking.
Keep your soak to about 10 minutes. Longer baths actually pull moisture out of the skin, which is the opposite of what you want. You can repeat these short baths several times throughout the day as needed for relief. Pat yourself dry gently with a soft towel rather than rubbing, since friction on sunburned skin will increase pain and can tear fragile, peeling skin.
What to Do Right After
The minutes immediately after your bath are critical. While your skin is still slightly damp, apply a fragrance-free, dye-free moisturizer to seal in the water your skin just absorbed. Moisturizers containing aloe vera or soy are particularly beneficial for sunburned skin. Aloe vera has its own mild anti-inflammatory effect, and soy-based ingredients help repair the skin’s moisture barrier.
Avoid anything with retinol, glycolic acid, or other active exfoliating ingredients until your sunburn has fully healed. These products are designed to increase skin cell turnover, which will irritate skin that’s already shedding damaged cells on its own. Stick with simple, soothing formulas for at least a week after the burn.