What Is Allergic Contact Dermatitis? Triggers, Diagnosis, and Relief

Allergic contact dermatitis (ACD) is an itchy skin rash that forms when the skin is exposed to allergens that trigger an immune response. It is a relatively common type of non-contagious eczema. The condition affects 1 in 5 people and can persist when unmanaged.

Experts often refer to ACD as a delayed-type hypersensitivity, as symptoms often occur hours and even days after initial exposure to an allergen. While ACD is non-life-threatening, it can result in very uncomfortable symptoms. Fortunately, several modes of treatment allow allergic contact dermatitis patients to live relatively symptom-free lives. 

Who Gets Contact Dermatitis?

Although ACD is quite common in the general population, certain factors make specific people more likely to develop the condition compared to others. These factors include:

Sex

Women are more likely to develop contact allergic dermatitis than men, with a 2011 study finding that the condition affects up to 66% of women compared to 33% of men. This is partly because around 8-11% of women are allergic to nickel, a metal frequently used in zippers, bra hooks, jewelry, buttons, and other common metallic products.

Age

As you age, structural and immunological changes in the skin increase your risk of skin allergies. Older patients with chronic wounds and static dermatitis tend to be oversensitized to topical medications and have a higher chance of developing allergic contact dermatitis upon contact with such medications.

Occupation

In most cases, repeated exposure to an irritant or allergen increases the risk of developing allergic contact dermatitis. People who work in certain occupations that involve proximity to allergens thus have a higher risk of contact dermatitis. These occupations include:

• Cleaners
• Florists
• Mechanics
• Plumbers and janitors
• Machinists
• Construction workers
• Hair stylists
• Cosmetologists
• Health care workers
• Cooks and hospitality employees

Genetics

Genes determine how well the skin acts as a barrier, whether the immune system overreacts upon contact with an allergen, and the severity of its inflammatory response. As such, some people are more genetically predisposed to ACD than others.

What Causes Allergic Dermatitis?

Allergic contact dermatitis is so common because most people regularly interact with allergens. Repeated exposure to these allergens increases the chance of allergic reactions, resulting in contact dermatitis. Here are some of the common causes of ACD:

Metal Hypersensitivity

Metal hypersensitivity affects around 10-15% of the population. Metals like nickel, cobalt, and chromium play a significant role in modern societies and can be found in various everyday items. This includes watches, coins, jewelry, earrings, bra hooks, and zippers. Repeated contact with these items can cause people to develop contact allergies. Since more women tend to have nickel allergies, they also suffer allergic contact dermatitis due to metal hypersensitivity at higher rates.

Plants

Plants such as poison ivy, cashew, mango, poison oak, and poison sumac cause contact dermatitis. When they are damaged, burned, or bruised, these plants produce an oil called urushiol that causes an allergic reaction when it touches the skin. Stinging nettle, leadwort, giant hogweed, ragweed, and baby’s breath can also trigger allergic reactions.

Chemical Allergens

Chemicals present in regularly used products also cause ACD. Stronger chemicals cause allergic symptoms relatively quickly, while weaker chemicals may require repeated exposure to cause symptoms. The following are some chemical irritants and allergens that can cause contact dermatitis:

• Latex or rubber
• Balsam of Peru
• Acrylates in nail cosmetics, hair extensions, and dental implants
• Adhesives
• Fragrances used in cosmetics, soaps, perfumes, and moisturizers
• Detergents and harsh soaps
• Drain cleaners
• Paraphenylenediamine in permanent hair dyes
• Paints and varnishes
• Acids
• Bleach
• Pepper spray
• Preservatives such as methylisothiazolinone
• Kerosene
• Plastics, epoxies, and resins
• Airborne chemicals like insecticide sprays and nail lacquer vapor

Babies may develop contact dermatitis from exposure to baby wipes, diapers, clothes with dyes and metal snaps, skin lotions or creams, and prescription antibiotics.

Personal Care Products

Cosmetic products tend to cause a lot of contact dermatitis as people use them daily. The fragrances in perfumes, soaps, and moisturizers contribute to ACD. Lotions, ointments, hair shampoos, dyes, bath products, and permanent wave solutions also contain fragrances and chemicals that can trigger ACD.

Sunblocks and sunscreens can also lead to facial contact dermatitis in some people when they react with sunlight and cause photoallergic contact dermatitis. Other products that may cause photoallergic reactions include coal tar products, lime skin oil, shaving lotions, and Sulfa ointments.

Occupational Exposure

Certain occupations require repeated contact with potential allergens. People who work in these fields tend to develop ACD at higher rates than those in other fields.

They include machinists, construction workers, hairdressers, beauticians, food handlers, and processors. Even doctors may develop contact dermatitis after repeated exposure to latex and rubber gloves.

These occupations often require repeated exposure to agents such as thiurams, epoxy resin, carbon mix, nickel, and formaldehyde which can trigger allergic reactions over time.

Dental and Oral Products

Oral and dental products can cause allergic reactions due to regular contact with the body. For instance, metals such as gold, nickel, cobalt, chromium, and palladium in dental work can eventually trigger allergic contact dermatitis symptoms.

Dental cement, toothpaste, and lozenges may also contain Balsam of Peru, a known allergen. Additionally, lip balms, lipsticks, mouthwashes, and flavorings in toothpaste can cause ACD.

Topical Medications

Exposure to certain topical medications can also result in the development of ACD. Preservatives in over-the-counter and prescription medications can trigger allergic reactions when the medication is applied to the skin. Topicals that can cause ACD include:

• Topical corticosteroids
• Topical antibiotics like bacitracin and neomycin
• Topical non-steroidal anti-inflammatory drugs (NSAIDs)
• Anti-itch creams that contain local anesthetic agents

Older people may be more sensitive to topical medications due to repeated exposure over their lifetimes. This increases their likelihood of developing contact dermatitis symptoms when they use topical medications.

Allergic Contact Dermatitis Symptoms

The speed with which allergic contact dermatitis symptoms develop will depend on the individual’s sensitivity to allergens, the degree of exposure, and the toxicity of the allergen or irritant. It generally takes anything from a few minutes to hours for the symptoms to show, and they can last between 2 to 4 weeks. However, some patients may only develop an allergy after months or even years of repeated exposure to an allergen.

In some cases, symptoms can spread from the original point of contact with the allergen. If an allergen gets onto your fingers, you can unknowingly transmit it to other parts of your body, such as your eyes, leading to generalized symptoms. Generally, contact dermatitis symptoms will occur on the hands, head, face, and neck  Here are some of the most common symptoms of allergic contact dermatitis:

• Swollen, warm, and tender skin
• Blisters and bumps that may have crusts and ooze pus
• Darker than usual leathery patches of skin
• Itchy rashes
• Dry, scaly, cracked skin
• Itchy, dry patches of skin under adhesive plaster
• Fissures or cuts on the hands
• Pain or burning at the point of contact

When to See a Doctor

Allergic contact dermatitis may not be life-threatening, but its symptoms can be incredibly painful. Symptoms such as rashes will sometimes begin to abate once you completely remove the allergen. This is especially true when a patient reacts relatively quickly to a new allergen. However, you should consider seeing a doctor if the rash fails to subside after eliminating the suspected allergen.

You should also see a doctor if the rash involves crucial areas such as the genitals, mouth, or eyes or if it spreads from the original point of contact. If you have symptoms such as fever and oozing blisters, seek medical attention immediately. Additionally, ensure you see a doctor if your nasal passages or eyes hurt due to exposure to poison ivy or burning weed.

Diagnosis

ACD diagnosis usually involves comprehensive reviews of a patient’s medical and life history followed by a patch test. Analyzing hobbies, home and work environment, and the products they use regularly allows physicians to narrow down the possible list of allergens. If this analysis uncovers a potential allergen, you will avoid it for some time to see if your symptoms improve.

Your physician will likely recommend patch tests if the symptoms do not abate. These tests involve wearing adhesive patches containing allergens like nickel and Balsam of Peru to see which triggers an allergic reaction. Your physician will instruct you to wear these adhesive patches for several days and check for allergic reactions at 48-hour intervals. Patch tests tend to be prescribed to patients with recurrent and severe contact allergic dermatitis.

At-home allergy tests can also be used to identify if seasonal or environmental allergies are causing your symptoms. This type of allergy testing only requires a small finger prick and can be done from the comfort of your home.

Prognosis

Patients with allergic contact dermatitis usually have a generally positive prognosis. If they can completely avoid the allergen that triggered the allergic reaction, allergic contact dermatitis symptoms will clear after 2 to 3 weeks. The symptoms may recur if the patient is exposed to the allergen again.

Continued exposure to allergens and harmful chemicals may lead to the development of chronic contact dermatitis. As such, people working in fields that expose them to allergens may have to find ways to limit this exposure to prevent their contact dermatitis from flaring up.

Treatment

Eliminating exposure to the allergen responsible for the allergic reaction is the best way to prevent reactions. Medical reviews and allergy tests will help determine what is causing your contact dermatitis to flare up. Avoiding allergens will significantly reduce your chances of developing allergy symptoms.

While limiting exposure is an effective method of reducing the likelihood that you’ll develop contact dermatitis, sometimes additional treatments are required to treat existing contact dermatitis reactions.

Topical Corticosteroids

Anti-itch creams like topical corticosteroids can alleviate the discomfort caused by itching and inflammation. This allows patients to recover from the skin condition with little discomfort and without causing further damage to the skin by scratching.

Antihistamines

Antihistamines can be used to help manage allergic contact dermatitis symptoms as they can temporarily reduce inflammation and itching. Antihistamines can also help manage additional allergy symptoms you’re dealing with.

Systemic Steroids

Your doctor may prescribe systemic steroids like prednisone if your contact allergy symptoms are severe, cover over 20% of the skin, and don’t respond to other treatments.

Emollient and Moisturizer Creams

Using moisturizer and emollient creams that contain ceramides regularly can help build up your skin's outermost layer and reduce its sensitivity to allergens. Hypoallergenic lotions can also help to reduce itchiness and inflammation in the skin.

Oral or Topical Antibiotics

Topical or oral antibiotics can be prescribed if a secondary bacterial infection accompanies allergic contact dermatitis. Patients will take these antibiotics alongside medication to reduce contact allergy symptoms.

Sublingual Immunotherapy

Sublingual immunotherapy reduces the body’s sensitivity to certain seasonal or environmental allergies over time. This treatment involves repeatedly taking allergy drops or allergy tablets containing small traces of your allergy triggers under your tongue to slowly desensitize your body to the allergen. Eventually, your body will become fully desensitized and stop reacting to the allergen.

Sublingual immunotherapy is a popular alternative to allergy shots and can be safely administered from the comfort of your home.

Take out Allergy Assessment

If you are tired of regularly dealing with allergy symptoms, choose Wyndly. Our allergy doctors will help you determine what seasonal or environmental allergies are causing your symptoms and create a personalized treatment plan to treat your allergies. Take our quick online assessment to begin your journey to an allergy-free future.