Overview

An allergy is the body's way of negatively reacting to a substance or allergen it flags as harmful. These allergens include pollen, pet hair, insect stings, latex, certain foods, etc. The immune system generally adapts to its immediate surroundings. If a foreign substance enters the body, it should be able to detect whether the substance is harmful or not. However, the immune system of people with allergies fails to do that for allergens, triggering a reaction. For instance, if pollen enters the body of a person allergic to pollen, his/her body won't understand that the allergen is harmless. The immune system fires up and releases antibodies immediately, paving the path for symptoms. When the human body detects an allergen, the immune system will start pumping out allergic antibodies IgE. Consequently, the human body produces a chemical known as histamine, which gives rise to all skin allergy symptoms. 
Skin conditions are one of the most common types of allergies that are treated and managed by an allergist/immunologist, a physician who has the specialized training and expertise to diagnose your condition and provide symptom relief accurately.

Types of Skin allergy:

Skin allergies are classified as follows based on the cause of the allergy:

Urticaria, or hives:
Hives are skin inflammation caused by the immune system's release of histamine. This causes tiny blood vessels to leak, resulting in swelling and itching. Angioedema is defined as swelling without itching in the skin's deep layers. Urticaria is divided into two types: acute and chronic. Acute urticaria occasionally occurs after eating a specific food or coming into contact with a specific trigger. Non-allergic triggers include heat and exercise, as well as medications, foods, insect bites, and infections. Chronic urticaria is rarely caused by a specific trigger, so allergy tests are typically ineffective. Genetic tests, on the other hand, can help with rare hereditary diseases that cause chronic urticaria. Chronic urticaria can last several months or years. Hives, while often uncomfortable and painful, are not contagious.
 

Eczema or Atopic Dermatitis:
Eczema is the most prevalent skin condition, particularly in children. It affects one in every five infants but only 10% of adults. Eczema is thought to be caused by "leakiness" of the skin barrier, which causes it to dry out and become susceptible to irritation and inflammation from a variety of external factors. In addition, some young children with eczema may flare up when exposed to a particular food. About half of patients with severe atopic dermatitis have the disease because they inherited a faulty gene in their skin called filaggrin, which is influenced by their race and ethnicity. Unlike urticaria (hives), histamine is not the sole cause of eczema's itch, so antihistamines may not be effective. Eczema is commonly associated with asthma, allergic rhinitis (hay fever), and food allergies. This pattern of progression is known as the atopic march.

Allergic Contact Dermatitis:
Allergic contact dermatitis develops when your skin comes into direct contact with an allergen. For example, if you have a nickel allergy and come into contact with jewellery containing even trace amounts of nickel, your skin may become red, bumpy, scaly, itchy, or swollen at the point of contact.
Contact with poison ivy, poison oak, and poison sumac can also result in allergic contact dermatitis. The red, itchy rash is caused by an oily coating on these plants. Touching the plant, as well as touching clothing, pets, or gardening tools that have come into contact with the oil, can all cause an allergic reaction.
 

Angioedema:
Angioedema is characterized by swelling in the skin's deep layers without itching. It is frequently associated with urticaria. Angioedema frequently affects soft tissues like the eyelids, mouth, and genitals. Angioedema is considered "acute" if it lasts only a few minutes or hours. Acute angioedema is frequently caused by an allergic reaction to medication or food. Chronic recurrent angioedema occurs when the condition returns over a long period of time, with each episode lasting from hours to several days. The majority of cases lack a clearly identifiable cause.

Hereditary Angiodema (HAE):
Hereditary angiodema (HAE) is a rare but serious genetic condition that causes swelling in several body parts, including the hands, feet, face, intestinal wall, and airways. It does not respond to standard angioedema treatment with antihistamines or adrenaline, so it is critical to see a specialist to rule out HAE and other genetic conditions.

Symptoms:

Skin allergies show some common signs like:

Rash
Itching
Redness
Swelling
Raised bumps
Scaling (flaking of skin)
Cracked skin

Causes:

If an allergic person comes in contact with allergens, he/she might experience a reaction within minutes. So, if a person feels that he/she has skin allergies, he/she must stay away from the following possible causes and allergens:

• Sunscreens 

• Cleaning products 

• Bug sprays 

• Certain plants (e.g., poison ivy)

• Latex 

• Certain metals (e.g., nickel)

• Certain chemicals

Risk Factors:

You might be more likely to develop an allergy if you:
Have a family history of asthma or allergies like hay fever, hives, or eczema; 
Are a child;
Have asthma or another allergic condition.

Possible complications:

Having an allergy increases the risk of certain other medical problems, such as:
Anaphylaxis: If you have severe allergies, you are more likely to experience this serious allergic reaction. Food, medications, and insect stings are the most common causes of anaphylaxis.
Asthma: If you have an allergy, you are more likely to develop asthma, which is an immune system response that affects the airways and breathing. In many cases, asthma is caused by exposure to an allergen in the environment.
Sinusitis and ear/lung infections: If you suffer from hay fever or asthma, you are more likely to develop these conditions.
 

Prevention:

Preventing allergic reactions is determined by the type of allergy you have. The general measures include the following:

Avoid known triggers: Even if you're treating your allergy symptoms, try to avoid potential triggers. If you are allergic to pollen, stay indoors with the windows and doors closed when pollen levels are high. If you are allergic to dust mites, vacuum and wash your bedding frequently.
Keep a diary: When attempting to determine what causes or worsens your allergic symptoms, keep track of your activities, what you eat, when symptoms occur, and what appears to help. This could help you and your provider identify triggers.

Wear a medical bracelet: If you've had a severe allergic reaction, a medical alert bracelet (or necklace) notifies others that you have a serious allergy in case you're unable to communicate.

When to Consult a Doctor?

If an individual is showing allergy symptoms like rashes or sores, he/she must visit a dermatologist as soon as possible. A skin rash may announce the onset of an allergy.

Although the rash might not be severe, there is a chance that it hints at an underlying medical condition.

If one suspects that he/she has skin allergies, he/she must look out for the following signs and symptoms:

• Heavy fever accompanied by a rash

• Rash all over mouth, eyes, and genitals

• Painful and itchy rash

• Rash starts spreading rapidly 

• Open sores (rash transforms into a blister)

• Rash spreads over the entire body

Diagnosis:

Doctors will initially examine the patient's skin to examine the symptoms. Then, they will perform a comprehensive analysis and ask the patient about the products he/she currently uses. This includes soaps, detergents, and other skincare products.

First, the doctor might suggest a patch test to determine the cause of dermatitis. The patch will contain many allergens in the form of tiny dots. This patch is pasted on the patient's back and kept for 48 hours. The patch must not get wet in this timeframe, so the patient must not sweat and take a bath.

Once the 48 hours is over, the patch is removed, and the location of the patches is marked. This helps during the final evaluation, which is done 72 to 96 hours after the patches are applied. If the patient's skin has reacted to any patches, the doctors will note the reaction. This will help them determine what allergens the patient must avoid.

Furthermore, this test is painless and doesn't involve needles poking into the patient's skin. Here are a few other tests that are performed to determine the presence of a skin allergy:

• Skin Prick Test

Also known as the puncture test or scratch test, the skin prick test essentially introduces over 50 different possible allergens to the bloodstream to check for multiple allergies simultaneously. This list of allergens generally includes certain foods, pollen, mould, pet dander, etc.

The skin prick test is carried out on the arms of adults and the backs of children. Remember that this test isn't as painful as it looks since the needles don't even penetrate the skin's surface thoroughly. As a result, there won't be any bleeding after the test, and the patient will only experience mild discomfort.

Once the pricking is done, the doctor will clean the site with rubbing alcohol and mark it. After this, a drop of allergen extract is applied at the test site; if the skin shows a reaction, the allergen is determined.

Additionally, two other substances are rubbed on the test site:

1. Glycerine: Most people's skin doesn't react to glycerine. However, if it does, the patient has very sensitive skin, and the doctor will perform the allergy testing much more cautiously.

2. Histamine: Histamine is the chemical responsible for an allergic reaction from inside the body. Therefore, most people's skin will react after rubbing histamine on it. However, if it doesn't, then there is a chance the skin might not respond to the allergen, even if an individual has an allergy to histamine.

• Skin Injection Test

The skin injection test is generally done to check if an individual is allergic to penicillin or insect venom. The test follows a similar procedure to the one above, except it uses an injection instead of a prick.

The doctor will wait 15 minutes for an allergic reaction to confirm the results.

• Allergy Blood Test

The allergy blood test, as the name suggests, draws a blood sample from the patient, which is then checked for its immunoglobulin (IgE) levels. If a person’s IgE levels are higher than usual, there is a chance that he/she is allergic to something. The test generally checks two primary things, namely:

1. Total IgE level: This measures all the IgE antibodies present in the patient's bloodstream.

2. Specific IgE level: A single allergen is introduced into the patient's bloodstream, and the test measures the IgE level response to each allergen.

Treatment:

Here are a few treatment options for skin allergies:

• Home Care

Home care for skin allergies depends on what is causing the patient's allergy. Generally, the first step to starting home care for skin allergies is to avoid the allergens altogether. If an individual comes in contact with the allergen, he/she can use calamine lotion, an oatmeal bath, or a simple cold compress to eliminate the itching.

Furthermore, if the allergic reaction is in a sensitive area, the doctor will prescribe a steroid cream to be used in the right amounts for maximum relief and efficiency.

• Medication

Allergy medication primarily consists of antihistamines, which counteract the effect of the chemical histamine released during an allergic reaction. These antihistamines can either be prescription medications or over-the-counter drugs. The doctor will prescribe allergy medication based on the severity of the patient's allergic reaction.

The various drugs used to battle skin allergies include:

• Antihistamines ( eg., Cetirizine, Azelastine, Loratadine, etc.)

• Corticosteroids (Eg., Betamethasone dipropionate, hydrocortisone, etc.)

• Leukotriene modifiers (e.g., Montelukast, Zafirlukast, etc.)

• Cromolyn sodium

If nothing else is easing the symptoms, the drug Singulair is used as the last resort. This drug is avoided since it can cause mood and behavioural changes, including suicidal thoughts, mental disturbance, and so on.

• Alternative Treatment

An alternative treatment method for allergies is immunotherapy. This treatment method requires the patient to take numerous injections over a few years. This will help the patient's body to get used to the allergy and keep the symptoms from returning in the future.

Risks & Complications if Left Untreated

Untreated allergies can cause quite a few complications down the line. The allergy symptoms and attacks might keep growing in severity and frequency. If this continues for a long time, the patient's immune system will weaken, leaving him/her vulnerable to complications such as fungal or bacterial infections (lungs, sinuses, ears, and skin).

Furthermore, the patient will be exposed to the risk of growing allergies to other allergens. Lastly, if the patient already has asthma, then delayed treatments for allergies will worsen his/her condition and leave him/her vulnerable to intense asthma attacks.

Additional Information

Skin allergies are an extensive term that includes several conditions. Still, some infections and diseases are most common due to their triggers. This section explains such well-known allergies along with their triggers.

1. Hives

These allergies can be identified by red bumps that can often be itchy. Some potential triggers of hives are as follows:

• Insect bites

• Reaction to sweat or heat

• Sunlight

• Stress

• Tight clothing or scratching

Allergic reactions to foods like eggs, shellfish, and nuts can also cause hives. Fortunately, hives fade in some days. Individuals can also use anti-itch drugs to combat these skin infections.

2. Eczema

This condition is characterised by a rash, prominently on the arms and knees. It results from a reaction to triggers like detergents, allergens, dust mites, pollen, and humidity.
Treating this itchy inflammation is straightforward. The doctor can prescribe suitable ointment or cream for external use. Such products help reduce the swelling in affected areas.

3. Angioedema

This skin allergy can accompany hives and occurs in the skin's deep layers. 
This condition can occur when the immune system perceives a harmless material as lethal. The allergic reaction leads to the release of antibodies to attack the trigger. Symptoms like swollen eyes, mouth, and difficulty in breathing are common among people with angioedema.

4. Skin Rash

In simple terms, skin rash implies a broad spread of lesions on the outer layer. These allergies are subjective and affect millions of individuals around the globe.
Common triggers of skin rashes include allergic reactions to the following:

• Plants like sumac

• Latex

• Rubber

• Beauty products

• Contact dermatitis

Rashes are primarily red and inflamed. In some cases, bacteria, fungi, and viruses can also lead to skin rashes. Some potential causes of rashes are flea bites, impetigo, shingles, scarlet fever, and mono.
Hydrocortisone cream is the most well-known solution for treating such rashes.

5. Acne

This skin condition is not always an allergic reaction. Acne can be a result of hormonal changes in teenagers or young adults. The sebum plugs hair follicles in this skin disorder, leading to a tender bump.

However, foods like potato chips, sugary drinks, milkshakes, and cornflakes can be potential triggers. In most cases, proper hygiene and avoiding irritants can reduce the onset of acne.