One thing is a fact: everyone has had skin allergies or knows someone who has. According to the World Health Organization (WHO), 40% of the world's population lives with frequent allergic conditions. Some, however, affect people more frequently, such as hives. The fact is that the skin is the body's largest organ, and because of its protective role, it is very susceptible to allergies.Learn now about the main ones.

Read more: Expired cosmetics and the dangers for the skin

What is a skin allergy anyway?

Skin allergies are exaggerated inflammatory reactions of the immune system to some substance, usually harmless, that can manifest themselves anywhere in the body. Thus, the main signs of these reactions include redness, itching, white or reddish lesions, scaling, and in the case of hives, depending on the severity, even life-threatening difficulty breathing.Allergies can have different causes, from a simple deodorant or perfume to medications, sun exposure, animal hair, insect bites, jewelry, sweat, food, clothing, fungi, etc.

The main skin allergies

Urticaria

The first is the appearance of raised, red plaques on the skin that usually cause intense itching. They can appear for various reasons, such as insect bites, food, the use of medicines, or contact with substances such as paints, latex, pollen, or animal saliva, for example.

Generally, these lesions disappear spontaneously within 24 hours, giving way to similar ones in different places on the body. Hives are treated with antiallergic drugs prescribed by the doctor. In addition, it is recommended to avoid heat, alcoholic drinks, and stress, because these are factors that worsen the allergy. When eating, it is recommended to avoid coloring, preservatives, and sausages (cold cuts, sausage),canned food, fish and seafood, chocolate, eggs, soft drinks, and artificial juices.

Depending on how long it lasts, hives can be acute, when the signs and symptoms disappear in less than six weeks, or chronic, i.e. when the symptoms last for six weeks or longer. Antiallergic medications are useful for relieving symptoms in cases of acute hives. Chronic hives, on the other hand, cannot be cured, but flares can be controlled with medications thatimprove the symptoms and, consequently, the quality of life of the patients.

Contact dermatitis

It usually occurs when there is contact with a substance that sensitizes the dermis; as a result, the skin produces an immune response that clinically manifests itself as red lesions, which often flake off and itch intensely; there may also be water bubbles that break, release liquid, and flake off.

It is usually localized according to its causative agent. When it is enamel, for example, it usually affects the face. More common in adults, this type of dermatitis only improves when the causative agent is removed.

The best treatment for contact dermatitis requires the following steps:

• Identify and avoid the substance causing the allergy (nickel and cosmetics, for example)
• Guide the substitution with alternative products, such as hypoallergenic ones
• Protect the skin, i.e. wear gloves when handling cleaning products, for example
• Treating inflammation primarily with topical medications such as corticosteroid ointments
• Restore the skin barrier by adequate hydration with the use of emollient creams.

Atopic dermatitis

This type of allergy is associated with rhinitis and the asthma Unlike hives, the lesions do not disappear quickly. It is a chronic disease, which can be genetic in nature, and presents with dry skin, itchy rashes, bleeding and crusting. The most common locations are the inner folds of the arms and legs, and the neck. In babies, the face is very affected. The condition can cause redness, dry skin anditching in the folds of the arms and legs.

The main recommendation for patients with atopic dermatitis is the use of odorless moisturizers several times a day.perfume, household cleaning products, and tobacco, in addition to other possible triggers such as cold or dry environments, sweating, anxiety or emotional stress, and rapid temperature changes.

Angioedema

Similar to urticaria, angiodema has the ability to reach much deeper layers of the skin, besides the mucous membranes, causing swelling of the lips, hands, feet and even the respiratory tract. The causes occur mainly after the consumption of certain foods, contact with animals, among others. It can evolve to anaphylactic shock (an abrupt and generalized allergic reaction, in which the blood pressureIt is important to seek urgent medical help if this occurs:

• Difficulty breathing,
• Tightness in the throat,
• Difficulty swallowing saliva,
• Loss of consciousness.

It sounds like a skin allergy, but it's not!

Some conditions are often confused with skin allergies, such as seborrheic dermatitis, herpes, and others:

Scabies

Known as scabies, scabies is transmitted between humans through direct contact with people or contaminated clothes and other objects. The mite's fecundation occurs on the surface of the skin. Soon after the male dies, the female penetrates the human skin, digging a tunnel, for a period of approximately 30 days. She then lays her eggs which, when they hatch, release larvae that return to the surface of the skinThis maturation process takes 21 days. It is worth remembering that animals such as cats and dogs do not transmit human scabies.

The main symptom of scabies is itching or pruritus, especially at night, causing excoriations between the fingers, in the armpits, on the part of the wrist that follows the palm of the hand, the areolae and genitals. Prevention consists, above all, in avoiding contact with contaminated people and clothes. In addition, when a patient is diagnosed with scabies, everyone who has had direct contact must beexamined and treated.

Herpes simple

Herpes simplex is a viral infection capable of producing blisters and sores in the mouth and genital area, and can also appear at the base of the nose and near the eyes. According to the Brazilian Society of Infectology (SBI), when an individual is infected, the virus remains in his or her body for life.developed the infection.

There are two types of herpes simplex:

• Type 1, which manifests itself by painful blisters or ulcers in and around the mouth, itching or burning of the lips before the appearance of small blisters, and redness of the lips.
• Type 2 appears in the genital area and on the internal mucous membranes, manifesting with small ulcers in this area of the body.

Herpes infection is treatable, but there is still no cure, just a few precautions that prevent flare-ups.

Shingles

Zoster, on the other hand, occurs through the reactivation of the varicella-zoster virus, causing reddish banded lesions on only one side of the face, chest, or back. These lesions are often preceded by burning pain or tingling even before they appear. After a few days these lesions become blisters and then ulcers.

Shingles is treated with antiviral drugs that must be started within 3 days of the onset of symptoms, in order to prevent post-herpetic neuritis - a condition of local pain that can last for months. Prevention can be done through the vaccine against shingles, indicated for people 50 years old and older.

Impetigo

According to the Brazilian Society of Dermatology, impetigo is a very common, highly contagious superficial bacterial skin infection most often seen on the face or extremities of the skin in children. It happens after a minor trauma to the skin or even after an insect bite, but can occur after other skin diseases, such as atopic dermatitis.

The skin is damaged and crusts, called miliocreses, form, because they have a honey-like color. Sometimes it can form blisters that rupture, when it becomes bullous impetigo. The lesion spreads to contiguous areas. Treatment is done by cleaning the wounds with soap and water and removing the crusts. For more localized infections, creams or ointments ofTopical antibiotics are used and, in more intense and diffuse cases, oral antibiotics.

Asteatotic dermatitis (dry skin)

Also called xerosis, asteatotic dermatitis is the medical term for dry skin. The result is dry, rough, taut skin that can progress to flaking or peeling. Inflammatory conditions such as atopic dermatitis and psoriasis always affect localized areas of skin with xerosis. Treatment is carried out through the use of emollients and guidelines such as taking short, warm baths.

Dermatitis Herpetiformis

Dermatitis herpetiformis or Duhring-Brocq dermatitis is a rare bullous skin disease with no known cause. What is observed is a reaction of the immune system against a region of the skin, which leads to the appearance of lesions of immunological origin, associated with an intestinal disease due to sensitivity to gluten (celiac disease).

It is a chronic disease, with a long duration, oscillating between periods of exacerbation of symptoms and periods of improvement. It affects mainly children, adolescents, and adult males.

The onset of the disease is gradual and is characterized by the formation of reddish lesions that evolve into vesicles (tiny blisters), progressing to large and tense eruptions with an arrangement similar to the appearance of herpes, hence the name herpetiform, although unrelated to the disease. The picture is often accompanied by intense itching that can cause abrasions, sores, and crusts.

Seborrheic Dermatitis

Seborrheic dermatitis, popularly called dandruff, is an inflammation of the skin that causes, above all, scaling and redness in some areas of the face, such as the eyebrows and corners of the nose, scalp, ears and chest. It presents periods of improvement and worsening of symptoms. The cause is not fully known, but may be related to the growth of a fungus called Malassezia In addition, inflammation can have a genetic origin or arise from external agents, such as allergies, situations of fatigue or emotional stress, low temperature, alcohol consumption, some types of medication, and excessive oiliness.

Nervous skin allergy

The release of the hormone cortisol, produced in times of stress, can also have repercussions on the skin, through the inflammatory process it causes in the long term. Besides stress, anxiety, depression, and low self-esteem can be associated with the manifestation or worsening of skin problems.

The most common skin diseases associated with emotional factors are atopic dermatitis, psoriasis, hives, and vitiligo.

Mycoses

Mycoses are infections that arise after fungal overgrowth, affecting the skin, scalp, nails, and moist areas of the body. Thus, their development is linked to factors such as a weakened immune system, diabetes, obesity, or excessive sweating.

The treatment depends on the type of mycosis, but it can be done with creams, lotions and talc, or oral medications, depending on the intensity of the condition. Nail mycoses are the most difficult to treat and long lasting.

Sun allergy

A sun allergy occurs when the skin presents a rash with redness, characterized by itching after sun exposure. It can also cause pain, skin patches, peeling, blisters, hives, and other symptoms. The cause is associated with genetic predisposition. The rashes of a sun allergy disappear on their own within 10 days.

What are the causes of skin allergies?

There are several causes for skin allergies, which can arise from contact - either single or repeated - with different allergenic factors. However, some agents are potential triggers for this type of reaction, and it is important to pay attention, such as

• Mites and fungi;
• Animal hair;
• Cosmetic products;
• Food;
• Pollen;
• Insect bites;
• Latex;
• Nickel (common metal in jewelry);
• Finally, medicines.

Symptoms of skin allergy

The most common symptoms of skin allergy are:

• Itching;
• Redness and burning;
• Scaling;
• Red spots on the skin;
• Red or white spots on the skin;
• Swelling;
• Rough skin;
• Sensitivity.

What are the complications?

Anaphylactic shock is the most severe form of hypersensitivity (allergy) reaction on the skin. Thus, signs and symptoms can begin within seconds of exposure to the agent or up to an hour later. Treatment for anaphylactic shock should begin promptly in the urgent and emergency health services. It is important to know that, despite being an emergency situation, it is controllable and reversibleThe best way to treat anaphylaxis and reduce mortality is to educate and guide patients and their families, as well as to prevent it.

Diagnosis of skin allergy

The diagnosis of skin allergy is primarily clinical; however, if there is a need for differential diagnosis, a skin biopsy can be performed, as well as a contact test to try to find the substance that is causing the allergy. Blood tests may also be ordered by the specialist.

Treatment of skin allergy

The best treatment for skin allergies depends on the patient's condition. It can be topical (applied directly to the skin), such as the use of ointments, creams, lotions, etc. or oral, with the use of antihistamine tablets, such as loratadine, desloratadine and ebastine in the treatment, or corticoids, such as prednisone. When the first symptoms appear, it is important to washthoroughly the region with water and soap with neutral pH.

Hydration is important for fighting allergies, because healthy skin creates a greater skin protection barrier, which prevents inflammation from reaching deeper layers of the skin.

Different medical specialties involved in the care

The diagnosis and treatment of skin allergy can be done by allergists as well as dermatologists or even general practitioners for adults and pediatricians for children.

What to ask the doctor in the consultation

Should I avoid the sun until the skin allergy is gone?

If your skin is already irritated or sensitive, exposure to UV rays and possible sunburn can cause more discomfort, so avoid sun exposure for the duration of your skin lesions.

Can foods cause skin allergies?

Yes, people with food allergies can develop hives and angioedema, for example. This is the case with shrimp allergy This can cause blisters or red patches on the body, as well as itching and swelling of the lips, tongue, eyelids, and throat.

How long does a skin allergy last?

At first, allergic skin reactions usually appear within a few minutes after contact with the allergen (the substance causing the inflammation). In some cases, however, inflammation can take several hours or up to three days to develop, so it is important to keep an eye on your memory to find out what substance or food caused the reaction. The skin allergy can persist for days,weeks or months, in cases of longer duration it is important to see a dermatologist or allergist.

How to prevent skin allergy?

Although we know that many types of skin allergies are unavoidable, the main tip for prevention is to avoid contact with the material or substance that triggered the allergy, and to seek a dermatologist to evaluate and indicate the most appropriate treatment.

Thus, to avoid or control allergies, the first recommendation is to moisturize the skin to maintain the protective barrier. In addition, use soaps suitable for your skin type (preferably those with neutral pH) and avoid hot baths (because they remove the natural oiliness of the skin). It is also important not to expose yourself to allergenic and irritating substances.

Read also: What are the best foods for summer skin care?

Source: Dr. Fátima Tubini , Specialist in Medical Sciences and Dermatology by AMB and Brazilian Society of Dermatology.

References: Brazilian Society of Dermatology (RJ) , São Paulo City Hall , Virtual Health Library , Chronicles of Daily Life , Brazilian Society of Dermatology .

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• Broad BA..Management of allergic contact dermatitis. Uptodate 2022.
• Weston WL, Howe W. Patient education: Eczema (atopic dermatitis) (Beyond the Basics). Uptodate 2022.