An antiallergic agent is a substance designed to treat or prevent the symptoms of an allergic reaction by interfering with the body’s response to substances it mistakenly identifies as harmful. The goal of antiallergic treatment is to reduce or stop the uncomfortable symptoms that occur when the immune system overreacts. This can range from relieving mild itching and sneezing to managing more significant respiratory issues.
The Body’s Allergic Response
An allergic reaction is the result of the immune system responding aggressively to a harmless substance, known as an allergen. When a person with an allergy is exposed to a trigger like pollen, their immune system produces Immunoglobulin E (IgE) antibodies. These IgE antibodies attach to immune cells called mast cells, which are found in connective tissues. This initial exposure sensitizes the mast cells, preparing them for future encounters with the same allergen.
Upon subsequent exposure, the allergen binds to the IgE antibodies on sensitized mast cells. This triggers the mast cells to degranulate, a process where they release chemicals into the surrounding tissues. The most prominent of these chemicals is histamine, which is responsible for allergy symptoms. Histamine causes blood vessels to dilate, leading to swelling and watery eyes, stimulates nerves to cause itching, and can contract airway muscles, resulting in breathing difficulties.
This cascade of events is an unnecessary and exaggerated defense against a harmless substance. The release of histamine and other inflammatory mediators is what antiallergic treatments are designed to counteract. This response can also lead to a late-phase reaction hours later, which involves other immune cells contributing to chronic inflammation.
How Antiallergic Agents Work
Antiallergic agents function by interrupting the allergic cascade at different points. The most common mechanism involves blocking histamine with medications known as antihistamines. These work by binding to histamine receptors (H1-receptors) on cells. By occupying these receptors, antihistamines prevent histamine from attaching and initiating the chain reaction that leads to symptoms like itching, swelling, and a runny nose.
Another approach targets mast cells directly to prevent them from releasing histamine and other inflammatory chemicals. This class of drugs, called mast cell stabilizers, fortifies the outer membrane of the mast cells, making them less likely to degranulate when an allergen is present. This preventative action is useful for managing ongoing allergic conditions but can take several days of use to achieve its full effect.
A third mechanism involves reducing overall inflammation. Corticosteroids accomplish this by suppressing the activity of multiple immune cells and inhibiting the body’s production of various inflammatory substances. Unlike antihistamines that target a single chemical, corticosteroids have a broader effect, making them effective for persistent allergy symptoms, including nasal congestion.
Types of Antiallergic Treatments
A variety of treatments are available to manage allergy symptoms. Antihistamines can be taken as pills, liquids, nasal sprays, or eye drops to relieve sneezing, runny nose, and itchy, watery eyes. They are divided into older, first-generation types that can cause drowsiness and newer second-generation versions that are less likely to have that side effect.
Corticosteroids are recognized for their anti-inflammatory effects and are available as nasal sprays to treat hay fever, creams for skin allergies, or inhalers for allergic asthma. Oral corticosteroids are typically reserved for severe allergic reactions due to the risk of side effects with long-term use.
Decongestants are designed to relieve nasal and sinus congestion by narrowing the blood vessels in the nasal passages. These are available in oral form or as nasal sprays and are sometimes combined with an antihistamine. Mast cell stabilizers come in forms like eye drops and nasal sprays and work by preventing the release of histamine, though they may take several days to become fully effective.
Distinguishing Antiallergic from Hypoallergenic
The terms “antiallergic” and “hypoallergenic” are often used for products aimed at sensitive individuals, but they describe different concepts. “Antiallergic” refers to a treatment or substance that actively works to prevent or counteract an allergic reaction. For example, an antiallergic pillowcase might be treated with a substance that neutralizes dust mites.
In contrast, “hypoallergenic” means a product is formulated to be less likely to cause an allergic reaction. This does not mean it is entirely free of potential allergens, but that common triggers have been minimized. A hypoallergenic lotion, for example, would be made without irritants like fragrances or dyes. Hypoallergenic bedding might use a tightly woven fabric that physically prevents allergens from penetrating the material.