Allergies
Frequency of allergic disease has doubled in the past few decades and currently it is estimated:
· 1 in 3 people will develop allergies at some time during life;
· 1 in 5 will develop atopic dermatitis;
· 1 in 6 will have an attack of urticaria;
· 1 in 10 people have asthma;
· 1 in 20 will develop a food allergy;
· 1 in 100 will have an anaphylactic reaction.
If untreated allergies might affect quality of life by interfering for e.g., with quality of sleep and worsen other conditions like asthma, sinusitis, eczema or urticaria.
Allergies like hay fever may be triggered by many allergens like wind-blown pollen, house dust mite, animal danders and mold spores. That means moving to a new area/city/country may temporarily relieve allergies. But since allergic people are prone to develop new allergies, symptoms are likely to reappear within a few years with exposure to new plants, or other sources of allergen.
It is also important to be aware continuous exposure to an allergen will not decrease allergy. For instance, indoor pets are associated with asthma and sensitivity often worsens with ongoing exposure. The best way to relieve symptoms of animal allergy is to avoid the animal or at least keep it out of the bedroom and carefully clean the flooring and wash the animal regularly to reduce the amount of allergen it shed.
And since animal allergens (particularly cat and horse allergens) can be carried on clothes, pet owners may sensitize other people who do not have pets themselves and provoke symptoms in sensitized individuals.
Allergy and Diet
Food allergy history can contribute to develop other types of allergies like eczema.
On the other hand, diet doesn’t seem to interfere with asthma or hay fever but exposure to wheat flour (when inhaled) can trigger asthma.
Food allergy usually has a rapid onset and includes severe and obvious reactions like rashes, throat swelling, vomiting or subtle worsening of atopic eczema.
Nuts, fish, shellfish, milk, eggs and wheat are the most common food allergies.
Allergy throughout Life
Some allergies can get better or worse in certain periods of life.
It is estimated about 85% of children with atopic dermatitis improve by their teenage years. Nevertheless, dry and irritable skin will most likely remain for life.
For asthmatic children there’s also a chance it gets better during adolescence, but it can occur it will worsen. Even if symptoms disappear completely, they may return later on in life, particularly with infections or exercise.
Allergic reactions to cow's milk, soy or egg in infants often resolve by the
time a child enters kindergarten, but others (such as peanut, tree nut or
seafood) usually persist for life.
Rhinitis
There are two types of rhinitis:
1. Allergic Rhinitis - the immune system mistakenly identifies a typically harmless substance as an intruder (allergen) and responds to it by producing Immunoglobulin E (IgE) antibodies. These antibodies travel to cells that release histamine and chemical mediators, causing an allergic reaction, that typically lead to symptoms in the nose, throat, eyes, ears, skin and roof of the mouth.
Most common allergens are pollen, dried skin flakes, urine and saliva found on pet dander, mold, droppings from dust mites and cockroach particles.
When symptoms of Allergic Rhinitis are triggered by pollen, they tend to flare up in the spring and fall and for this reason it is also classified as seasonal allergic rhinitis or hay fever.
When symptoms of Allergic Rhinitis are triggered by indoor allergens, they usually remain all year-round. That’s why it is also known as perennial allergic rhinitis.
Allergic rhinitis causes inflammation in the nasal lining and eyes. Because of this people suffering from this condition are more sensitive to certain substances present in smoke or strong odors and to weather changes involving temperature and humidity of the air. They are also more prone to allergic conjunctivitis and worsen of asthma symptoms.
2. Nonallergic Rhinitis - the immune system is not involved and there is no allergy reaction even if symptoms like runny nose and nasal congestion are present all year-round.
Rhinitis symptoms include itching (in the nose, roof of the mouth, throat and/or eyes) runny and stuffy nose, sneezing and tearing and/or dark circles under the eyes.
Regarding diagnosis skin tests or blood tests are the most common methods for determining allergic rhinitis triggers.
Treatment & Management
Allergic Rhinitis
In order to manage allergic rhinitis patients, have to learn how to avoid allergens that trigger the symptoms.
In case of hay fever preventive treatment can be recommended. Antihistamines and nasal steroids can be started before tree pollen is in the air (early spring). As a result, histamine and other chemicals will not be release and allergy symptoms are prevented or much less severe.
Management of symptoms includes antihistamine, decongestant and corticosteroid drugs (usually oral or nasal forms).
Immunotherapy based on allergy shots is another possibility that can provide long-term relief of symptoms for some patients, even after treatment is stopped.
This kind of treatment can also be considered for cased of allergic asthma, conjunctivitis or stinging insect allergy.
Nonallergic Rhinitis
The treatment of choice for nonallergic rhinitis involving inflammation of the nose is nasal corticosteroid sprays.
Nasal ipratropium spray should be preferred for cases of severe runny nose.
If nasal congestion is the major problem, decongestant pills or sprays can be used, but the sprays should not be used for more than four days.
Azelastine nasal spray may also be helpful in case of congestion.
Skin Allergies
Irritated skin can be caused by a variety of factors. These include immune system disorders, medications and infections. When an allergen is responsible for triggering an immune system response, then it is an allergic skin condition.
Itching, redness and swelling are common to most skin allergies. Yet there are some differences that help in the diagnosis of specific conditions.
Eczema
Eczema, also known as Atopic Dermatitis, is the most common
skin condition, especially in children.
It is estimated to affect one in five infants but only around one in fifty adults.
Skin typically becomes itchy and red or dry patches that may be exudative can be seen. In case fluid crusts over when scratched, it means secondary infection is also present.
Affected body areas vary with patient’s age.
In infants, eczema often appears on the face.
Children are prone to have the rash at the bends of the elbow joint, wrists, behind the knees and behind the ears.
Adolescents and young adults typically have the rash in the same locations as children, as well as on the hands and feet.
It is now thought to be due to fragility of the skin barrier, which causes it to dry out and become prone to irritation and inflammation by many environmental factors.
In about half of patients with severe atopic dermatitis, the disease is due to inheritance of a faulty gene in their skin called filaggrin. These patients often have hand eczema with excessive little lines on the skin of their palms.
Eczema is also often linked with asthma, allergic rhinitis or food allergy that can actually make eczema symptoms worse.
Therefore, infants and young children with more severe eczema should be evaluated for food allergy.
Eczema Management
To manage symptoms regular use of a sodium laurel sulfate free body wash and a good moisturizer is the basic principle.
Since scratching causes more rashes it’s important to avoid it. For this purpose, cotton undergarments and body suits help protect the skin.
Unfortunately, since the itch of eczema is not caused by histamine release, antihistamines do not work to control it. They might only be useful to induce sleep at night time helping patients to relax.
When inflammation worsens topical steroids or calcineurin inhibitors might also be required.
Antibiotics may be prescribed if a skin bacterial infection is suspected as a trigger for eczema flare-up. In this case symptoms include crusting, oozing and pain.
Please note oral steroids should be avoided, as although they are effective the eczema usually returns when the medicine is stopped.
Allergic Contact Dermatitis
Allergic Contact Dermatitis occurs when the skin comes in direct
contact with an allergen and becomes red, scaly, itchy or swollen at the point
of contact.
It might be painful but is never contagious.
Common allergens include nickel, poison ivy, poison oak and poison sumac.
Urticaria
Urticaria, also known as Hives, is skin inflammation
triggered when the immune system releases histamine, which is responsible for
itchiness.
It can occur anywhere on the body and red and white raised bumps that range in size can be seen.
There are two types of urticaria:
1. Acute Urticaria - occurs after eating a particular food or coming in contact with a particular trigger.
It can also be triggered by non-allergic causes such as heat or exercise, as well as medications, foods or insect bites.
2. Chronic Urticaria - rarely caused by specific triggers and so allergy tests are usually not helpful.
It can last for many months or years.
The choice treatment for this problem is oral antihistamines control the itch and recurrence of the rash and avoidance of triggers.
Angioedema
Angioedema is swelling in the deep layers of the skin.
It often appears on the face around the eyes, cheeks or lips but can also occur on hands, feet, genitals, or inside the bowels or throat.
There are different types of angioedema:
1. Acute Angioedema - if the condition lasts only a short time such as minutes to hours.
It is usually due to an allergic reaction to medications or foods.
2. Chronic Angioedema – if angioedema is recurrent, i.e., the condition returns over a long period of time.
It typically does not have an identifiable cause.
3. Hereditary angioedema (HAE) - is a rare, but serious genetic condition involving swelling in various body parts including the hands, feet, face, intestinal wall and airways. It does not respond to treatment with antihistamines or adrenaline.
Angioedema is treated primarily with oral antihistamines. Nevertheless, is it useful to enquire the patient about medicines in use since for e.g., some antihypertensive medicines can cause this type of swelling.
Food Allergy
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Keep in Mind...
Allergy ≠ Intolerance
Food intolerance and food allergy are two different problems even if some of
the symptoms are similar.
In food allergy, or oral allergy syndrome (OAS) there is an allergen that triggers a response in the immune system and it might be life-threatening which does not occur with food intolerance.
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Food allergy occurs when the immune system overreacts to a particular protein found in that food and symptoms can be seen even if contact occurs with just a very small amount of allergen.
Symptoms can include skin redness, itching of skin/eyes/nose, sneezing, teary eyes, vomiting, stomach cramps, diarrhea or angioedema.
Some cases can lead to anaphylaxis. In this situation prompt medical assistance is required. Therefore, it is crucial to stay alert and be able to detect signs of throat tightness, difficulty in breathing and tingling in the hands, feet, lips or scalp.
OAS is often first diagnosed in young children, though it may also appear in older children and adults.
Cow’s milk, eggs, fish, peanuts, shellfish, soy, tree nuts and wheat are responsible for most of the cases.
Since there is no treatment for OAS the most important is avoiding coming in contact with food proteins that can cause an allergic reaction. Patients education on food labels reading is very important.
In case of milder reaction it is possible to use antihistamines to relieve symptoms.
Being allergic to a food may also result in being allergic to a similar protein found in something else because the immune system recognizes this similarity and develops what is called a cross-reactivity reaction.
For example, patients with ragweed allergy often develop reactions to bananas or melons.
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FPIES and EoE
Food Protein-Induced Enterocolitis Syndrome (FPIES), sometimes referred as delayed food allergy, is a severe condition causing vomiting and diarrhea. In some cases, symptoms can progress to dehydration and shock brought on by low blood pressure and poor blood circulation.
Much like other food allergies, FPIES allergic reactions are triggered by
ingesting a food allergen. Although any food can be a trigger, the most common
culprits include milk, soy and grains. FPIES often develops in infancy, usually
when a baby is introduced to solid food or formula.
Eosinophilic Esophagitis (EoE) is an allergic condition causing inflammation of the esophagus. It might develop because of allergy or sensitivity to particular food protein. Clinical data suggests it is related with other allergic disorders such as asthma, rhinitis or dermatitis.
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- Course creator: Lurdes Pastor
- Course creator: Eliana Sequeira
- Course creator: Molly WONG