ENT allergy sufferers
Allergy describes a wide range of conditions, some of which are rare and some very common. In healthy individuals, when the immune system registers a substance as a threat, B cells, a type of white blood cell, produce antibodies. This is a process known as sensitisation and is part of the normal immune response. In allergic individuals, the immune system misidentifies a harmless substance as a threat. Therefore, an allergy is an unnecessary immune response to an innocuous substance (termed an allergen). Allergens are usually proteins (called antigens) found in a non-infectious allergy-causing substance (for example pollens or dust mites), which ultimately trigger the immune system to respond in a way that can be harmful, causing tissue damage and serious disease. These harmful immune responses are termed hypersensitivities and often cause a number of undesirable reactions which can lead to wheezing, coughing, oedema (swelling), or, in extreme circumstances, anaphylaxis. IgE-mediated allergy is broadly characterised as a Type 1 hypersensitivity. Other hypersensitivity reactions (II, III and IV) are mediated by other antibody classes, immune cells or cellular components. Common IgE-mediated allergies include food allergies, wasp venom and hay fever (see Box 1). Some people may have an inherited tendency towards allergies, a condition known as atopy. Atopic individuals are more prone to asthma, eczema and hay fever (the atopic triad).
How does allergy develop?
It is true in most cases that a person cannot have an allergic reaction to a substance that he or she has never come across. Encountering an allergen once is therefore usually necessary to develop an allergy. The process through which a person’s body becomes sensitive to a given allergen is known as sensitisation.
Sensitisation
When allergens enter the body, antigen presenting cells (immune cells that capture incoming substances and present them to other immune cells, initiating a cascade of immune responses) at body surfaces, capture and present them to immune cells, particularly T cells (in a similar manner as if the allergen was a foreign invading microbe). Through a number of immune interactions between T cells and B cells, B cells produce allergen-specific IgE antibodies. Once released into the blood, IgE binds to mast cells (the major allergy immune cell), as well as other immune cells such as basophils. Some, but not all, individuals who are sensitised will develop an allergic reaction on re-exposure to the allergen.
Re-exposure to allergen
It is possible for an individual to go their whole life carrying allergen-specific IgE bound mast cells without ever experiencing an allergic reaction or even being aware of the allergy. However, upon re-exposure to the offensive allergen, binding of the allergen to IgE on mast cells can initiate an aggressive and immediate immune response. Mast cells are granular cells, meaning they contain many secretory granules which, when activated, release their contents into the blood stream (see picture on right) . In the case of allergy, binding of an allergen to IgE-mast cells results in their rapid degranulation and the release of inflammatory compounds, including histamine, which contribute to local inflammation and the symptoms associated with allergy. In the respiratory tract, for example, inflammation results in mucus secretion and allopurinol without a doctor prescription vasodilation in the nose and lungs, which can lead to wheezing and difficulty breathing. In order to offset the immediate symptoms of an allergic reaction, people with allergies can take anti-histamines, a class of drug that limits the action of histamine on the body. In extreme cases of anaphylaxis, patients may require an adrenaline injection. In addition to early-phase symptoms, a number of symptoms can occur several hours after exposure to the allergen and can even last upwards of weeks. Late-phase reactions can result in similar symptoms, but also tissue destruction and continued immune cell recruitment. Anaphylaxis to foods is more common in young people whereas severe reactions in older people are more commonly triggered by insect venom. What is oral allergy syndrome
Oral allergy syndrome (OAS), a type of food allergy, is an allergic reaction that is confined to the lips, mouth and throat.
OAS most commonly occurs in people with asthma or hay fever from tree pollen who eat fresh (raw) fruits or vegetables. Other pollen allergies may also trigger OAS. Adults appear to be more affected than children.
Causes of oral allergy syndrome
Oral allergy syndrome is due to a cross-reactivity between plant proteins from pollen and fruits or vegetables. When a child or adult with pollen allergy eats a raw fruit or vegetable, the immune system sees the similarity and causes an allergic reaction.
Interestingly, many patients with oral allergy syndrome can eat the same fruits or vegetables when they are cooked. The cooking process changes the protein enough that the immune system does not recognize the food as being the same as the pollen anymore.
Sometimes foods in the same botanical family will also cause reactions. Examples are potato and carrot, parsley and celery, or apple and pear.
Cross-reactivity
Pollen Potential Cross-reactive Foods
Ragweed Bananas, melons (watermelon, cantaloupe, honeydew) zucchini, cucumber, dandelions, chamomile tea
Birch Apples, pears, peaches, apricots, cherries, plums, nectarines, prunes, kiwi, carrots, celery, potatoes, peppers, fennel, parsley, coriander, parsnips, hazelnuts, almonds, walnuts
Grass Peaches, celery, melons, tomatoes, oranges
Mugwort Celery, apple, kiwi, peanut, fennel, carrots, parsley, coriander, sunflower, peppers
Alder Celery, pears, apples, almonds, cherries, hazelnuts, peaches, parsley
Latex Bananas, avocado, kiwi, chestnut, papaya
Signs and symptoms of OAS
Rapid onset of itching or swelling of the lips, mouth or throat are the most common symptoms of OAS. Other symptoms may include irritation of the gums, cheapest augmentin eyes or nose.
Symptoms normally appear within minutes of eating the offending food. Symptoms are also often worse during augmentin 875/125 mg coupon the spring and fall pollen seasons.
Treatments for OAS
In most cases, OAS does not require medical treatment. It is best to avoid the offending foods. Often just peeling or cooking the food will reduce the effects.
At times, an antihistamine can effectively relieve the symptoms. In adults and children with severe recurrent OAS, immunotherapy (allergy shots) to the pollen have been useful.What is allergic rhinitis?
Allergic rhinitis is the medical term for hay fever or nasal allergies. By definition, allergic rhinitis is swelling of the nasal passages caused by allergens. It’s important to note that while many people refer to it as hay fever, it is not caused by hay. Nor does is cause a fever. Allergic rhinitis is triggered by having allergies. You have an allergy when your body overreacts to things that don’t cause problems for most people. These things are called allergens.
There are 2 forms of allergic rhinitis:
Seasonal (hay fever):Caused by an allergy to pollen and/or mold spores in the air. Pollen is the fine powder that comes from flowering plants. It can be carried through the air and is easily inhaled. Symptoms are seasonal and usually occur in spring, late summer, and fall. This is the most common form of allergy.
Perennial:Caused by other allergens such as dust mites, pet hair or dander, or mold. Symptoms occur year-round.
Symptoms of allergic rhinitis
Your symptoms can vary, depending on the severity of your allergies. Symptoms can include:
Sneezing
Coughing
Itching (mostly eyes, nose, mouth, throat and skin)
Runny nose
Stuffy nose
Headache
Pressure in the nose and cheeks
Ear fullness and popping
Sore throat
Watery, red, or swollen eyes
Dark circles under your eyes
Trouble smelling
Allergic rhinitis can last several weeks, longer than a cold or the flu. It does not cause fever. The nasal discharge is thin, watery, and clear. Nasal discharge from a cold or the flu tends to be thicker. Itching (mostly in the eyes, nose, mouth, throat, and skin) is common with hay fever but not with a cold or the flu. Sneezing occurs more with hay fever. You may even have severe sneeze attacks.
What causes allergic rhinitis?
If you have allergies, your body releases chemicals when you are exposed to an allergen. One such chemical is called histamine. Histamine is your body’s defense against the allergen. The release of histamine causes your symptoms.
Hay fever is an allergic reaction to pollen. Pollen comes from flowering trees, grass, and weeds. If you are allergic to pollen, you will notice your symptoms are worse on hot, dry days when wind carries the pollen. On rainy days, pollen often is washed to the ground, which means you are less likely to breathe it. Your allergies can vary depending on the time of year:
Allergies that occur in the spring (late April and May) are often due to tree pollen.
Allergies that occur in the summer (late May to mid-July) are often due to grass and weed pollen.
Allergies that occur in the fall (late August to the first frost) are often due to ragweed.
Allergens that can cause perennial allergic rhinitis include:
Mold is common where water tends to collect, such as shower curtains and damp basements. It can also be found in rotting logs, hay, and mulch. This allergy is usually worse during humid and rainy weather.
Animal dander.The skin, saliva, and urine of furry pets such as cats and dogs are allergens. You can be exposed to dander when handling an animal or from house dust that contains dander.
Many allergens, including dust mites, are in dust. Dust mites are tiny living creatures found in bedding, mattresses, carpeting, and upholstered furniture. They live on dead skin cells and other things found in house dust.
How is allergic rhinitis diagnosed?
If your symptoms interfere with your daily life, see your family doctor. Your doctor will ask you questions about your symptoms and medical history and perform a physical exam. Keeping a record of your symptoms over a period of time can help your doctor determine what triggers your allergies.
Your doctor may want to do an allergy skin test to determine what you are allergic to. Tiny amounts of allergens are applied to your skin. You will feel tiny pricks that are usually not painful. Your doctor will observe and record the way your skin reacts to each allergen.
Your doctor may also decide to do a blood test, such as the radioallergosorbent test (RAST). This test identifies antibodies in your blood that determine what you’re allergic to. Once your allergens are identified, you and your doctor can decide the best treatment.A physical allergy is an allergic reaction triggered by a physical stimulus.
(See also Overview of Allergic Reactions.)
A physical allergy differs from other allergic reactions because the trigger is a physical stimulus. Physical stimuli include the following:
Cold
Sunlight
Heat or other stimuli that cause sweating (such as emotional stress or exercise)
Vibration
Minor injuries (such as those due to scratching)
Physical pressure
For some people, symptoms occur only in response to a physical stimulus. For some people who have other allergies, a physical stimulus makes symptoms worse.
Causes of Physical Allergy
What causes a physical allergic reaction is not understood. One theory suggests that the physical stimulus changes a protein in the skin. The immune system then mistakes this protein for a foreign substance and attacks it. Sensitivity to sunlight (photosensitivity) is an example. Ultraviolet light in sunlight changes proteins in the skin, which the body then identifies as foreign and attacks. Photosensitivity is sometimes triggered by the use of drugs (such as antibiotics), some cosmetics (such as skin creams, lotions, and oils), or other substances.