What doctors wish patients knew about “summer finger bumps”

When summer begins, many people look forward to beach days, barbecue and other outdoor activities. But for some, the arrival of warmer weather also brings unwelcome guests: small, itchy blisters on their hands and feet. Sometimes referred to as “summer finger bumps,” blisters are a symptom of the skin condition dyshidrotic eczema, and they can cause discomfort and frustration. But knowing what to expect and how to find relief is key.

While the exact prevalence of dyshidrotic eczema is unknown, it is considered a common cause of hand dermatitis in adults, accounting for 5% to 20% of cases in the U.S. Also, about half of dyshidrotic eczema cases happen in people who have allergic reactions when they touch an antigen, such as nickel and cobalt in jewelry.

The AMA’s What Doctors Wish Patients Knew™ series gives physicians a platform to share what they want patients to understand about today’s health care headlines.

In this installment, Robert Bai, MD, a dermatologist at Viriginia Mason Franciscan Health in Federal Way, Washington, discusses what patients need to know about dyshidrotic eczema.

Virginia Mason Franciscan Health is a member of the AMA Health System Program, which provides enterprise solutions to equip leadership, physicians and care teams with resources to help drive the future of medicine.

“Dyshidrotic eczema manifests as tiny blisters on the hands or feet,” Dr. Bai said. “People classically describe this as ’tapioca-like.’ So, like those small one-to-two-millimeter bubbles that are found in tapioca pudding.  

“On your hands, these small blisters are filled with fluid, are somewhat deep and you can’t pop them,” he added. “Although they are small, these blisters can be quite uncomfortable,  with significant burning or itching symptoms.”

“They stay there for a while and they can be quite irritating when they’re there,” Dr. Bai said.

“For a lot of patients—which is why we probably don’t see most of them—dyshidrotic eczema comes and goes,” Dr. Bai said. “Sometimes a patient’s dyshidrotic eczema appears with the summer heat and goes away in the cooler months, which is why it’s called summer finger bumps.”

“A lot of times, people can figure out what is potentially triggering their rash or blisters on their hands and try to avoid those potential triggers,” he said. “If we’re able to give them an effective regimen, consisting of topical steroids and sometimes even pills, for the vast majority of folks can quickly improve within a week or two.”

“Eczema predisposition can be the sole cause of their dyshidrotic eczema,” Dr. Bai said. “The other common cause is maybe they’re touching something that they’re allergic to, such as metals or chemicals.”

“People can also get irritation just from moisture alone,” he said. “For example, if they wash dishes a lot and their hands are always wet or they do a lot of wet work—that can contribute to dyshidrotic eczema.”

Additionally, “there are other potential causes such as medications, ultraviolet light, stress, and warm weather,” Dr. Bai said, adding that while the summer heat can contribute to dyshidrotic eczema, “it’s hard to prove, but I’ve certainly heard from patients where they’ve gotten sun exposure and it’s hard to say whether it’s from the sunlight or from heat or a combination of the two that contributes to it.”

Dyshidrotic eczema is typically seen “in teenagers and young adults and less commonly seen in older individuals,” Dr. Bai said. “It’s also more female predominant.”

“With regards to prevalence, it’s a little difficult to say … but we see it quite frequently in the clinic,” he said. While it is “less common than psoriasis or eczema, it’s one of those conditions where a lot of people don’t seek care and as a result, it’s hard to quantify because sometimes people only have it for a few weeks a year and they don’t seek medical care.”

“This is one of those conditions that we love to see because you can just take a look at it and you can diagnose the condition right away,” said Dr. Bai. “Beyond that, dermatologists will often check to see if there are any rashes elsewhere, especially on their feet to see if there are any rashes there such as a fungal rash like athlete’s foot.”

“If there is suspicion for fungus, you can test for that through doing skin scraping in the clinic, but majority of the time it’s just from examining the rash,” he said.

“The more difficult part of the clinic visit is figuring out what’s causing the rash,” said Dr. Bai. “That is why dermatologists often ask about what patients do for work, what they do at home or outside of work and home, how often it occurs and if there are any triggering factors.

“You really have to do a thorough evaluation of these patients to figure out what the cause or trigger of their rash is,” he added. “Pinpointing a cause can sometimes be challenging.”

“It’s always important to target the underlying cause, whether it’s because they’re getting their hands wet all day long, their hands are exposed to irritants or heat.” Dr. Bai said. “If you don’t identify the underlying culprit here, you can’t get to the root cause of the problem, and it’d be a recurrent thing.”

“If you can find the underlying cause, great. Target that. If you can’t pinpoint the culprit, then there are plenty of things that you can do to get rid of the rash as well,” he said. “If you do nothing else other than finding the culprit and removing the culprit, the condition will improve, although it may take several weeks or longer.”

“Regardless of the culprit, you want to get rid of the blisters,” Dr. Bai said. “There are a couple ways to target these small blisters.”

“You can use a strong topical steroid, which is something you have to go see a physician for. So it is not something available over the counter,” he added. “And then there are these over-the-counter astringent solutions that draw the moisture away from your skin—one of them is called Domeboro soak.”

Using the soak “can certainly be very helpful when you do have the blisters,” Dr. Bai said, emphasizing it is “good for symptomatic relief.”

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When it comes to using over the counter hydrocortisone cream, “it’s really weak with what you can get over the counter,” Dr. Bai said. “They can be helpful, but they work very slowly to get the condition better.”

“In theory, if you were to have dyshidrotic eczema, if you were to use something over the counter such as hydrocortisone cream, it would get better if you also get rid of the underlying trigger as well,” he said.

“Light therapy is oftentimes a very good strategy, but logistically it’s very difficult because you have to go to a dermatology clinic to have this treatment two to three times a week, at least initially,” Dr. Bai said. “When I say light therapy, I have to be mindful that we’re not talking about getting extra sun or going to a tanning salon. Those are much riskier ways to get light and can increase risk of skin cancers.”

“Stress exacerbates many skin conditions,” Dr. Bai said. “Whether that’s psoriasis, eczema or dyshidrotic eczema—they will get worse with stress.”

“So, talking to your therapist if you have one or talking to your primary care physician, and being mindful of your stress levels can help to lower stress,” he said. “A lot of times I ask patients if their condition gets better when they’re on vacation.

“It’s a good way to gauge and figure out whether it’s something related to higher stress levels at school or work, or even something they are exposed to at school or work,” Dr. Bai added. “And that can sometimes help with figuring out what the cause is.”

For dyshidrotic eczema, “if it’s a few blisters, it’s relatively mild and goes away in a short amount of time, many people don’t come see the doctor,” Dr. Bai said. Even if it is mild, “it’s always safer to see a medical professional because it’s hard to say whether you have the right diagnosis because sometimes it could be herpes, fungus or something more significant and you certainly don’t want to ignore that.”

“It’s always worthwhile to see a medical professional to obtain the correct diagnosis and an effective regimen,” he said.