Psoriasis and Allergies: What’s the Connection?

 From everydayhealth.com

Psoriasis — a skin disease in which cells build up quickly, typically causing red or discoloured, scaly, and itchy patches — is often seen in people with other allergic or inflammatory conditions. These conditions include eczema (atopic dermatitis), nasal or respiratory allergies (allergic rhinitis), and asthma.

While estimates vary, one study found that among U.S. adults, people with psoriasis were more than twice as likely as those without psoriasis to have asthma or allergic rhinitis. And while psoriasis and eczema are distinct skin conditions, research shows they share some common features, including skin barrier dysfunction.

Here’s what you should know about the connection between psoriasis and allergies, including how treating or controlling one condition could affect the other.

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The Psoriasis-Allergy Connection

There are some notable similarities and differences between psoriasis and allergic conditions.

“Psoriasis, seasonal allergies, and eczema are all immune-mediated. They are attributed to immune system dysfunction,” says Lauren Taglia, MD, PhD, a dermatologist at Northwestern Medicine in Geneva, Illinois.

But psoriasis tends to involve different pathways in the immune system compared with allergic conditions. For example, one analysis found that in skin biopsies (tissue samples) from people with psoriasis or eczema, different kinds of immune cell clusters were found for each condition. What’s more, inflammation was seen in different kinds of cells in blood samples taken from people with each condition.

Both genetic and environmental factors may contribute to psoriasis as well as conditions like eczema and allergic rhinitis. People with one allergic condition are also more likely to develop another allergic condition, possibly due in part to genetic factors.

Allergic conditions are often activated by a known allergen, such as pollen, foods, or substances that contact your skin. Psoriasis flares can also have a known trigger, but these triggers may be less specific and predictable than is typically seen in allergic conditions. Psoriasis triggers can include infections, skin injury, weather conditions, smoking or second-hand smoke, alcohol consumption, and certain prescription drugs.

For allergic conditions, treatment typically focuses on preventing exposure to known allergens and possibly taking medicines to reduce your immune system’s reaction and improve symptoms. For psoriasis, there are medications that treat disease flares as well as injected or infused medications that can keep some people symptom-free for months or even years.

Does Controlling One Help Control the Other?

For people with both psoriasis and allergies, it’s possible but not a certainty that the two conditions could interact.

“Skin allergies can exacerbate psoriasis” by increasing inflammation in the body, says Jeffrey Weinberg, MD, a clinical professor of dermatology at Mount Sinai in New York City. “If we minimize allergies, it could minimize flares of psoriasis because of that inflammatory effect.”

But allergies are typically considered a less common psoriasis trigger, so there may be limited interaction between the conditions in many people. “Allergies typically do not play a role in psoriasis, as a cause or as part of therapy,” says Kim B. Sanders, a certified physician assistant and associate professor of dermatology at Oregon Health & Science University in Portland.

It’s unlikely that most medications for psoriasis will directly help with allergies, or vice versa. “Because they use different ‘highways’ in the immune system, a treatment for one doesn’t always help the other,” says Soo Jung Kim, MD, PhD, an associate professor of dermatology at the University of Washington School of Medicine in Bellevue. That’s particularly true when it comes to biologic drugs for psoriasis, Dr. Kim says.

But some treatments could be beneficial for both psoriasis and eczema, in particular. These include topical steroid creams and ointments, light therapy, and skin moisturizers and protectants.

Risk of Drug Interactions

In some rare cases, taking a biologic drug for psoriasis could increase your risk for allergic conditions — especially eczema.

“Biologic medication that successfully shuts down the psoriasis pathway might ‘tilt’ the immune system, potentially triggering or worsening eczema symptoms,” says Kim. When this happens, it’s known as paradoxical eczema.

One study found that about 1 percent of biologic drug injections or infusions for psoriasis resulted in paradoxical eczema. This risk was lower for IL-23 inhibitors compared with tumour necrosis factor inhibitors (two groups of biologic drugs), and higher for people with a history of eczema or respiratory allergies.

The opposite effect may also happen, Kim says, with biologic drugs used to treat allergic conditions potentially causing psoriasis or making it worse — although this evidence is currently limited to case reports.

But in most cases, it’s unlikely that a treatment for psoriasis or allergic conditions will have any effect on the other disease. “Overall, high-quality evidence that treating one condition reliably improves or worsens the other remains limited,” says Kim.

Lifestyle Modifications That Could Help Both

Certain lifestyle measures could be beneficial for both psoriasis and allergic conditions:

• Optimize skin care. Avoiding harsh cleansers and regularly using a moisturizer can be helpful for both psoriasis and eczema, according to Kim.
• Be aware of triggers. Knowing what activities or environmental exposures tend to make your psoriasis or allergies worse can help you avoid them, or at least plan ahead to make sure you’re treating them effectively.
• Focus on a healthy diet. Following a Mediterranean-style diet and “eating the rainbow” of fruits and vegetables can help ensure you get the nutrients needed to support your immune system and may help reduce inflammation, says Dr. Taglia.
• Manage a healthy body weight. “Obesity is strongly associated with psoriasis severity,” says Kim, adding that body fat is linked to pro-inflammatory immune system proteins. “Obesity also worsens asthma and allergic rhinitis outcomes,” she adds.
• Don’t smoke. Smoking is linked to more severe psoriasis and worse asthma control, and quitting can help with both conditions, Kim says.
• Minimize stress. To help reduce stress, “I think how we move our bodies matters,” says Taglia, which can mean getting regular exercise or performing mind-body practices like yoga. “And just making healthy choices in how we consume the world,” when it comes to things as varied as food, alcohol, and information.

The Takeaway

• Psoriasis and allergic conditions like asthma or eczema are both immune-mediated, and people with psoriasis are significantly more likely to have these co-occurring conditions.
• While treating one condition rarely controls the other, managing skin allergies may help reduce psoriasis flares by minimizing overall body inflammation.
• In rare cases, certain biologic medications for psoriasis can trigger eczema symptoms, a reaction known as paradoxical eczema.
• You can support your immune system and help manage both conditions by maintaining a healthy weight, avoiding smoking, and using gentle skincare products like moisturizers and mild cleansers.
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• https://www.everydayhealth.com/skin-conditions/psoriasis-and-allergies-connection/