Allergies, also known as allergic diseases, are various conditions caused by hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include hay fever, food allergies, atopic dermatitis, allergic asthma, and anaphylaxis. Symptoms may include red eyes, an itchy rash, sneezing, coughing, a runny nose, shortness of breath, or swelling. Note that food intolerances and food poisoning are separate conditions.
Annatto is an orange-red condiment and food coloring derived from the seeds of the achiote tree, native to tropical parts of the Americas. It is often used to impart a yellow to red-orange color to foods, but sometimes also for its flavor and aroma. Its scent is described as "slightly peppery with a hint of nutmeg" and flavor as "slightly nutty, sweet and peppery".
Hair coloring, or hair dyeing, is the practice of changing the color of the hair on humans' heads. The main reasons for this are cosmetic: to cover gray or white hair, to alter hair to create a specific look, to change a color to suit preference or to restore the original hair color after it has been discolored by hairdressing processes or sun bleaching.
p-Phenylenediamine (PPD) is an organic compound with the formula C6H4(NH2)2. This derivative of aniline is a white solid, but samples can darken due to air oxidation. It is mainly used as a component of engineering polymers and composites like kevlar. It is also an ingredient in hair dyes and is occasionally used as a substitute for henna.
A food allergy is an abnormal immune response to food. The symptoms of the allergic reaction may range from mild to severe. They may include itchiness, swelling of the tongue, vomiting, diarrhea, hives, trouble breathing, or low blood pressure. This typically occurs within minutes to several hours of exposure. When the symptoms are severe, it is known as anaphylaxis. A food intolerance and food poisoning are separate conditions, not due to an immune response.
Contact dermatitis is a type of acute or chronic inflammation of the skin caused by exposure to chemical or physical agents. Symptoms of contact dermatitis can include itchy or dry skin, a red rash, bumps, blisters, or swelling. These rashes are not contagious or life-threatening, but can be very uncomfortable.
A patch test is a diagnostic method used to determine which specific substances cause allergic inflammation of a patient's skin.
Allergic contact dermatitis (ACD) is a form of contact dermatitis that is the manifestation of an allergic response caused by contact with a substance; the other type being irritant contact dermatitis (ICD).
Balsam of Peru or Peru balsam, also known and marketed by many other names, is a balsam derived from a tree known as Myroxylon balsamum var. pereirae; it is found in El Salvador, where it is an endemic species.
Lotion is a low-viscosity topical preparation intended for application to the skin. By contrast, creams and gels have higher viscosity, typically due to lower water content. Lotions are applied to external skin with bare hands, a brush, a clean cloth, or cotton wool.
Egg allergy is an immune hypersensitivity to proteins found in chicken eggs, and possibly goose, duck, or turkey eggs. Symptoms can be either rapid or gradual in onset. The latter can take hours to days to appear. The former may include anaphylaxis, a potentially life-threatening condition which requires treatment with epinephrine. Other presentations may include atopic dermatitis or inflammation of the esophagus.
Skin allergy testing comprises a range of methods for medical diagnosis of allergies that attempts to provoke a small, controlled, allergic response.
Dogs are susceptible to allergies much like their human companions. Most allergies occur in dogs over 6 months old. A dog that is repeatedly exposed to a particular allergen becomes sensitized to it, and the immune system overreacts to a subsequent exposure, most commonly manifesting in the form of skin irritation. Some of the signs are redness, itching, hair loss, and recurring skin infections from the irritation. Skin irritation may be generalized or localized. The dog may be more prone to scratching and licking at the irritated site, further exacerbating the problem.
Henna is a reddish dye prepared from the dried and powdered leaves of the henna tree. It has been used since at least the ancient Egyptian period as a hair and body dye, notably in the temporary body art of mehndi resulting from the staining of the skin using dyes from the henna plant. After henna stains reach their peak colour, they hold for a few days, then gradually wear off by way of exfoliation, typically within one to three weeks.
Allergen of the Year is an annual "award" voted upon by the American Contact Dermatitis Society. The purpose of the award is "to draw attention to the agents causing the most significant clinical effects, those that are underrecognized and those that have become obsolete or for which exposure patterns have changed".
Perfume intolerance or perfume allergy is a condition wherein people exhibit sensitivity or allergic reactions to ingredients in some perfumes and some other fragrances. It is a form of multiple chemical sensitivity, a more general phenomenon for this diagnosis.
Fish allergy is an immune hypersensitivity to proteins found in fish. Symptoms can be either rapid or gradual in onset. The latter can take hours to days to appear. The former may include anaphylaxis, a potentially life-threatening condition which requires treatment with epinephrine. Other presentations may include atopic dermatitis or inflammation of the esophagus. Fish is one of the eight common food allergens which are responsible for 90% of allergic reactions to foods: cow's milk, eggs, wheat, shellfish, peanuts, tree nuts, fish, and soy beans.
Shellfish allergy is among the most common food allergies. "Shellfish" is a colloquial and fisheries term for aquatic invertebrates used as food, including various species of molluscs such as clams, mussels, oysters and scallops, crustaceans such as shrimp, lobsters and crabs, and cephalopods such as squid and octopus. Shellfish allergy is an immune hypersensitivity to proteins found in shellfish. Symptoms can be either rapid or gradual in onset. The latter can take hours to days to appear. The former may include anaphylaxis, a potentially life-threatening condition which requires treatment with epinephrine. Other presentations may include atopic dermatitis or inflammation of the esophagus. Shellfish is one of the eight common food allergens, responsible for 90% of allergic reactions to foods: cow's milk, eggs, wheat, shellfish, peanuts, tree nuts, fish, and soy beans.
Metal allergies inflame the skin after it has been in contact with metal. They are a form of allergic contact dermatitis. They are becoming more common, as of 2021, except in areas with regulatory countermeasures.
Disperse blue dyes are blue-colored disperse dyes. Disperse dyes are used to color textiles. Disperse blue dyes are used to produce blue and other dark colors. Like other disperse dyes, they are only slightly soluble in water. However, they can be a source of water pollution.
