Overview

When the warmer seasons start coming closer and the weather changes, illnesses come and go with it too. The most common ailment would be allergies that affect many people worldwide. Allergies can have various causes and range from mild to severe. In some cases, we can experience pruritus (itching) alongside allergies. In this article, we will aim to discuss the details of the two and give an overview about each one.

Pruritus

Overview

Pruritus is a common symptom that affects many people who have skin or systemic conditions, and with time, chronic pruritus can develop a dynamic of its own without a link to an underlying cause.¹ It can be debilitating and affect our quality of life. So, what is pruritus? It is defined as an itch that causes a desire to scratch, however, people suffering from this tend to pinch, rub or damage their skin with devices in hopes to relieve this itch.¹ It can be a skin’s reaction to an allergen (immune response), heat, or skin dryness, among other causes that will be listed below.²

Chronic pruritus (CP) is defined as itching that can last for 6 weeks or more and it tends to increase with age; although the data on its prevalence is limited, it is estimated that around 60% of elderly (> 65 years) have mild to severe pruritus weekly.¹

Pruritus is interesting as it can manifest itself in different diseases; in some cases, it can appear before the diagnosis of the underlying disease by years (e.g. premonitory pruritus) and in other cases it can be an early indicator of neoplastic disease e.g. Hodgkin Lymphoma.¹

Some examples of the systemic diseases that can induce pruritus are included in table 1

Table 1. Systemic illnesses that can cause pruritus.¹

Causes and symptoms

Pruritus can rise due to multiple causes such as:³

• Reactions to heat or allergens: this can cause allergies, hives, or heat rash(prickly heat).
• Skin conditions such as dandruff, eczema or psoriasis
• Fungal skin infections e.g. thrush, ringworm, athlete’s foot
• Parasitic infections or insects living on the skin: scabies, head or pubic lice
• Pregnancy
• Menopause: pruritus can occur after menopause and usually gets better with time

Visible symptoms of pruritus include:²

• Itchiness
• Blisters, spots, or bumps
• Dry, cracked, or scaly skin
• Leathery or thick-looking skin
• Redness

Treatment and prevention

Having pruritus can be severe and lead to skin damage, hence, it is important to treat and sort out. Usually, the treatment will be related to the cause, however, a GP might prescribe a lotion or cream to help with the symptoms.³ Blood tests and medical history assessment will be important to provide the appropriate treatment.³ Sometimes, a visit to the dermatologist will be needed for further assessment.

There are steps that can be taken to prevent and decrease pruritus such as:^1,3

• Wearing soft clothing that is permeable to air such as cotton or silk
• Low room temperature during nights
• Moisturise skin daily especially after showers or baths to avoid dryness
• Bathing in lukewarm water for no more than 20 minutes. It is also possible to use oatmeal or potassium permanganate, and dab the skin dry after the bath
• Holding a cool damp towel to the skin
• Avoid perfumed soaps, deodorants and moisturisers

Allergies

Overview

Allergies are among the most common diseases around the globe.⁴ They arise when our body has a strong reaction to a specific allergen.^5,6 There are different types of allergies, and they include the following:^5,6,7,8

Drugs/medications

Strong allergic reactions to certain medications can occur in some people. These are known as ADRs, or adverse drug reactions. Studies reported that due to females (assigned at birth) having higher levels of antibody IgE during adulthood compared to males (assigned at birth), females have a higher rate of ADRs. These reactions are either a side effect of the medication or immunological response facilitated through the adaptive or innate immune systems that drive drug allergy. Nonetheless, a lot of the self-reported drug allergies tend to be a side effect to the medication taken rather than an actual allergy due to an immune origin. However, drug allergies do still occur e.g. allergy to penicillin.

Food

Food allergy can be one of the interesting allergies; they happen when someone eats a specific food antigen that is usually harmless to healthy people. Once ingested, this antigen or allergen causes an immune response in these patients which can be mild to severe. It is worth noting that allergies are different from food intolerance or toxins and pathogens found in some foods. A food intolerance is a toxic, metabolic, pharmacological mechanism that sometimes can be uncharacterised. To elaborate on this, someone may have a milk intolerance because they lack the lactase enzyme rather than having an immune reaction, hence this makes it an intolerance and not an allergy. Food allergies can also be classified into IgE, non-IgE mediated or both together. Some examples of foods that people can have allergies to include walnuts, wheat, shellfish, peanuts, eggs and many others.

Environmental

This form of allergy affects about 20% of the population globally. It has also been on an increase in recent years due to genetic variations alone. There are global trends that can also affect its prevalence; for example, the increase in urbanisation and quick population growth affects our day-to-day activities, such as diets, time indoors or even physical activity, as well as being exposed to environmental hazards, such as air pollution, mould and smoking, can increase prevelance of allergic reations. 

Allergy mechanisms

As mentioned previously, allergies can be IgE, non-IgE mediated or both. Hence, we will discuss these in more detail:^7,9,10

IgE mediated

This type of reaction is rapid with symptoms appearing within minutes to hours from ingesting the causing agent. For example, in food allergies, people will be sensitised to a specific food allergen. This means that there will be detectable levels of allergen specific IgE in the blood which can then promote the development of food allergy. These allergens or antigens are mistaken as pathogens in the body, and this causes our bodies to release an inflammation signal, this in turn activates T cells and changes them into T helper cell 2 (Th2). This leads to more inflammation and activation of the B-cells with the release of specific IgE resulting in an allergic reaction. Severe reactions can lead to anaphylaxis.

Non-IgE mediated

Unlike IgE mediated, these reactions tend to be chronic and are more complex to control, so avoiding the causing agent, like food, is not enough. Non-IgE mediated has other agents of the immune system in play and their mechanism is not as clearly understood like the IgE mediated mechanism. The symptoms tend to be more localised in the intestines, but they can also affect the skin and lungs. Some examples include food protein-induced enterocolitis syndrome (FPIES).

Combination IgE/non-IgE

This type includes a combination of IgE and non-IgE mechanisms and includes skin disorders such as atopic eczema or eosinophilic gastrointestinal disorders such as eosinophilic esophagitis.

Symptoms and detection

When facing allergies, symptoms vary based on the type. Some of the symptoms include:¹¹

• Runny nose
• Sneezing
• Pain in the eyes and tenderness in the forehead, cheeks and around the eyes
• Hives or itchiness
• Coughing/wheezing or breathlessness
• Swelling in the eyes, mouth, throat, or lips
• Diarrhoea or bloating
• Feeling tired and ill

When detecting allergies, there are several tests that can be done such as:¹¹

• Skin prick test
• Patch test
• Blood tests
• Diet changes

Treatment

There are several steps that we can take to lower the symptoms of allergies including:¹¹

• Taking medication like antihistamines, steroid tablets and creams
• Using EpiPens in severe cases of allergy
• Immunotherapy, which is also referred to as desensitisation, is done in a controlled setting through a medical professional. The procedure is done by exposing the individual to the causing agent over time to help the body adapt and decrease the severe reactions to it

Summary

Pruritus and allergies go hand in hand. While pruritus is a symptom (itchy skin), allergies are the medical condition. There are many causes of pruritus that can be as simple as dry skin ranging to more complex causes such as being a symptom of underlying illness like lymphomas. While pruritus occurs in allergies, it does not always have to be present. Allergies have different mechanisms being IgE mediated or non-IgE mediated or a mix of the two. It is important to consult with a healthcare professional for the appropriate diagnosis and getting the right treatment to have a better quality of life.