How to Tell the Difference Between Nummular Eczema and Ringworm
It’s often difficult to distinguish between nummular eczema and ringworm, so it’s always best to be evaluated by a dermatologist, say experts.
Published On: May 28, 2021
Last Updated On: Sep 19, 2023
If you live with eczema, choosing the right sunscreen is complicated: it’s important to protect your skin while avoiding any ingredients that might cause a flare. We spoke with Dr. JiaDe “Jeff” Yu, board-certified dermatologist at Massachusetts General Hospital, to better understand what people with eczema should consider when choosing their sunscreen.
To choose the right type of sunscreen, it may help to understand why a sunscreen might trigger a flare in the first place. According to Dr. Yu, there are two common types of adverse reactions to sunscreen: the first is topical irritation; the second is an allergic reaction; and both responses have their unique underlying cause.
Dr. Yu explained that irritant reactions to sunscreen are the most common. “Irritant reactions occur immediately,” he said. “They’re often characterized by stinging and burning.” This is usually caused by a high alcohol content in the sunscreen. Looking for a sunscreen without alcohol, or a minimal amount of alcohol in it, can be challenging. “The amount of alcohol in a sunscreen is difficult to suss out just by reading the ingredients alone,” Dr. Yu said. “There is little to no regulation for this labeling.” Dr. Yu recommended using “thicker sunscreen balms such as sticks,” and looking for sunscreens labeled “sensitive skin.” The best course of action would be to find a sunscreen without any alcohol at all. The NEA Seal of AcceptanceTM Product Directory does not allow any sunscreens with alcohol and can help inform your individual search.
In the case of an allergic reaction to sunscreen, the symptoms may appear more slowly. The flaring is typically caused by an ingredient that takes longer for the skin to absorb. “Allergic reactions to sunscreen are rare and typically occur within a few hours or days,” said Dr. Yu. “The most common allergens are usually the inactive ingredients such as fragrances and preservatives. The reaction is usually characterized by itching.”
In the event of an allergic reaction, you may need to consult with an allergist. With a skin test or blood test, an allergist can help identify the specific ingredients to avoid in the future. Dr. Yu also noted that some people do have allergic reactions to the active ingredients in sunscreen, too, though this is less common. He said that chemical filters such as oxybenzone (benzophenone-3), avobenzone and benzophenone-4 can sometimes lead to a delayed allergic reaction. Certain sunscreens include these chemicals to absorb the sun’s rays1, as opposed to mineral sunscreens that use ingredients like zinc oxide or titanium dioxide to deflect the sun.1
Dr. Yu also advised people with eczema to be aware of a rare allergic reaction called photoallergic contact dermatitis.”² This occurs when ingredients in the sunscreen remain inert and harmless on your skin until the UV rays activate them and cause flaring in your skin. One ingredient that has been found to cause photoallergic contact dermatitis is octocrylene,³ especially in adults who use lotions with the drug ketoprofen; octocrylene has also been found to trigger a contact allergy in children.³ Consider avoiding all products that contain octocrylene, as this ingredient is not allowed in any Seal of Acceptance products.
For those who would like to determine whether their reaction to sunscreen is due to an irritant or allergic reaction, Dr. Yu recommends speaking with a board-certified dermatologist who specializes in this area. “Testing products used on the skin such as sunscreen is almost exclusively done by dermatologists with an interest in patch testing and allergic contact dermatitis. These doctors are members of the American Contact Dermatitis Society.” To find a member of the American Contact Dermatitis Society in your area, go to https://www.contactderm.org/find/.
For someone living with eczema, finding the right sunscreen may involve some trial and error. Your first step is reading the label. If you have experienced topical irritation due to the alcohol content, consider trying an alcohol-free mineral sunscreen with NEA’s Seal of Acceptance. The active blocking ingredients should feature zinc oxide and/or titanium dioxide, as opposed to alternative non-organic chemical compounds excluded by the Seal criteria.
Once you’ve selected a possible sunscreen, the next step is to apply a patch test before using the sunscreen more extensively on the rest of your body. A patch test is simple: just dab a pea-sized amount to the inside of your wrist or elbow, then leave the area unwashed for 24-48 hours, and watch for any reactions such as itching, redness, flaking, pain or rash. If your skin doesn’t flare, the next step is to try using the sunscreen in the sun. In the absence of any photoallergic reaction, you may be ready to apply the sunscreen liberally and frequently, while remembering to stay hydrated, too.
If the patch test results in an allergic reaction, or if the allergic reaction happens once you’re out in the sun, it’s time to schedule an appointment with a dermatologist with expertise in contact dermatitis.
Once you’ve selected a sunscreen that works for your skin, apply at least 30 minutes before going outside. Apply to all exposed surfaces, and don’t be afraid to use a lot, about one ounce or more. In addition to your sunscreen, don’t forget these additional steps to ensure a holistic approach to skin protection while you’re outside:
Ready for some time in the sun? Get your search for the perfect sunscreen started with our Product Directory for sunscreens that have earned the NEA Seal of AcceptanceTM.
References
1. All about sunscreen: Why you need it. How it works for you. Skin Cancer Foundation. Updated January, 2021. Accessed April 14, 2021. https://www.skincancer.org/skin-cancer-prevention/sun-protection/sunscreen/
2. Ngan, V. What is photocontact dermatitis? DermNet NZ: All About Skin: Updated January 2006. Accessed 4/21/ 2021. https://dermnetnz.org/topics/photocontact-dermatitis/
3. De Groot AC, Roberts DW. Contact and photocontact allergy to octocrylene: A review. Contact Dermatitis. 2014;70(4):193-204.doi: 10.1111/cod.12205
4. Sun-protective clothing: A safe, simple way to keep the rays at bay. Skin Cancer Foundation. Updated June, 2019. Accessed April 14, 2021. https://www.skincancer.org/skin-cancer-prevention/sun-protection/sun-protective-clothing/
It’s often difficult to distinguish between nummular eczema and ringworm, so it’s always best to be evaluated by a dermatologist, say experts.
Karin Stoddart, 20, a college student from Seattle, finally has her eczema under control after battling with two insurance companies to stay on her doctor-prescribed medication.
Learn which plants won’t irritate your eczema — and can also help purify the air in your home.
Christina Crowley, from Berkeley, California, shares how she became a NEA board member — recently NEA’s Board Chair in 2023 — as well as a donor and Itching for a Cure fundraiser.
Evidence-based articles, expert-sourced lifestyle tips and stories from your community.