Also known as Queensland Itch, Seasonal Recurrent Dermatitis (SSRD) , Summer Itch or more technically, "Culicoides" Hypersensitivity.

Sweet Itch is a medical condition in equines caused by an allergic response to the bites of "Culicoides" midges. It may be found in any horses and ponies, especially in the warmer regions. It may also occur, too, in other equines. It is also found in Canada, Australia, the US and many other parts of the world.

Symptoms of an allergic reaction to animals may include itchy skin, nasal congestion, itchy nose, sneezing, chronic sore throat or itchy throat, swollen, red, itchy, and watery eyes, coughing, asthma, or rash on the face or chest.

A hypersensitivity reaction to specific allergens (protein molecules causing an extreme immune response in sensitised individuals) in the saliva of "Culicoides" midges. There are multiple allergens involved, although some workers claim that the larger proteins (of molecular weight 65kDa) are the most important. These allergens appear to be cross-reactive across many species of "Culicoides" - i.e. many different varieties of midges produce similar allergens, giving the same effects upon horses.

The hypersensitivity response is mediated by IgE, an antibody produced by the horse's immune system which binds the allergens, causing a cascade production of histamine and cytokines which make the horse's skin inflamed and itchy. Of these, histamine appears the most important in the initial phase of reaction.

Mud fever, also known as scratches or pastern dermatitis, is a group of diseases of horses causing irritation and dermatitis in the lower limbs of horses. Often caused by a mixture of bacteria, typically "Dermatophilus congolensis", and "Staphylococcus spp", mud fever can also be caused by fungal organisms (dermatophytes). Photosensitization, chorioptic mange mites, contact dermatitis and other conditions also contribute to some cases. This condition is also known as "dew poisoning," "grease heel," or "greasy heel".

Mud fever affects most horses and ponies during winter and early spring, resulting in painful sores and scabs, which in severe cases can make a horse lame. Mud fever most commonly affects the pastern and heel area but can also affect the upper leg, the belly, and in some cases the neck area (also known as Rain Scald). Non-pigmented skin tends to be more severely affected.

In medicine, animal allergy is hypersensitivity to certain substances produced by animals, such as the proteins in animal hair and saliva. It is a common type of allergy.

Mud fever is a chronic but progressive dermatitis. It affects all breeds of horses, but it is most common in heavy draft horses like the Clydesdales. It often starts as a small red ulceration of the skin in the plantar pastern region of the legs. The lesions then grow and develop scaling with the formation of a crust, hair loss, edema, oozing and the release of a malodorous exudate. Skin fissures and papillomatous lesions can develop in chronic cases.

Zirconium granulomas are a skin condition characterized by a papular eruption involving the axillae, and are sometimes considered an allergic reaction to deodorant containing zirconium lactate. They are the result of a delayed granulomatous hypersensitivity reaction, and can also occur from exposure to aluminum zirconium complexes. Commonly, zirconium containing products are used to relieve toxicodendron irritation. The lesions are similar to those from sarcoidosis, and commonly manifest four to six weeks after contact. They appear as erythrematous, firm, raised, shiny papules. Corticosteroids are used to ease the inflammation, but curative treatment is currently unavailable.

The most common type of eruption is a morbilliform (resembling measles) or erythematous rash (approximately 90% of cases). Less commonly, the appearance may also be urticarial, papulosquamous, pustular, purpuric, bullous (with blisters) or lichenoid. Angioedema can also be drug-induced (most notably, by angiotensin converting enzyme inhibitors).

Some of the most severe and life-threatening examples of drug eruptions are erythema multiforme, Stevens–Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), hypersensitivity vasculitis, Drug induced hypersensitivity syndrome (DIHS), erythroderma and acute generalized exanthematous pustulosis (AGEP). These severe cutaneous drug eruptions are categorized as hypersensitivity reactions and are immune-mediated. There are four types of hypersensitivity reactions and many drugs can induce one or more hypersensitivity reactions.

Cutaneous disorders in musicians include frictional injury ("fiddler's neck"), hyperhidrosis, acne mechanica and vascular compromise. Other agents of irritant and allergic contact dermatitis may be rosewood, Makassar ebony, cocobolo wood, African blackwood, nickel, reed, propolis (bee glue), chromium and paraphenylenediamine. Patch testing can be performed for identification of the cause.

Identifying a drug allergy can sometimes be the hardest part. Sometimes drug allergies are confused with nonallergic drug reactions because they both cause somewhat similar reactions. Symptoms of a drug allergy can include, but are not limited to, the following list.

- Hives

- Itching

- Rash

- Fever

- Facial swelling

- Shortness of breath due to the short-term constriction of lung airways or longer-term damage to lung tissue

- Anaphylaxis, a life-threatening drug reaction (produces most of these symptoms as well as low blood pressure)

- Cardiac symptoms such as chest pain, shortness of breath, fatigue, chest palpitations, light headedness, and syncope due to a rare drug-induced reaction, eosinophilic myocarditis

Atopy (atopic syndrome) is a syndrome characterized by a tendency to be “hyperallergic”. A person with atopy typically presents with one or more of the following: eczema (atopic dermatitis), allergic rhinitis (hay fever), or allergic asthma. Some patients with atopy display what is referred to as the “allergic triad” of symptoms, i.e. all three of the aforementioned conditions. Patients with atopy also have a tendency to have food allergies, allergic conjunctivitis, and other symptoms characterized by their hyperallergic state. For example, eosinophilic esophagitis is found to be associated with atopic allergies.

Atopic syndrome can be fatal for those who experience serious allergic reactions, such as anaphylaxis, brought on by reactions to food or environment.

The main cause is a type-I hypersensitivity reaction to products containing abietic acid, such as the rosin/colophony, which is commonly used as a friction-increasing agent. Players of bowed string instruments (violin, viola, cello, double bass) rub cakes or blocks of rosin on their bow so it can grip the strings. Ballet and flamenco dancers sometimes rub their shoes in powdered rosin to reduce slippage before going on stage. Gymnasts, baseball pitchers and ten pin bowlers use rosin to improve grip. Common locations of this contact dermatitis are hands, face and neck.

The use of podiatry drills, in the absence of engineering controls and personal protective equipment, is an occupational hazard to the healthcare provider. Nail dust collected during foot care procedures performed in office settings has been found to contain keratin, keratin hydrolysates, microbial debris, and viable fungal elements, including dermatophytes (most commonly "Trichophyton rubrum") and saprotrophs. Exposure to nail dust and the associated risk will vary with the policies and practices in place, the type of podiatry drill used, therapy technique, frequency of procedures, personal protective equipment utilized and the use of ventilation systems.

A drug allergy is an allergy to a drug, most commonly a medication, and is a form of adverse drug reaction. Medical attention should be sought immediately if an allergic reaction is suspected.

An allergic reaction will not occur on the first exposure to a substance. The first exposure allows the body to create antibodies and memory lymphocyte cells for the antigen. However, drugs often contain many different substances, including dyes, which could cause allergic reactions. This can cause an allergic reaction on the first administration of a drug. For example, a person who developed an allergy to a red dye will be allergic to any new drug which contains that red dye.

A drug allergy is different from an intolerance. A drug intolerance, which is often a milder, non-immune-mediated reaction, does not depend on prior exposure. Most people who believe they are allergic to aspirin are actually suffering from a drug intolerance.

Atopy is a predisposition toward developing certain allergic hypersensitivity reactions.

Atopy may have a hereditary component, although contact with the allergen or irritant must occur before the hypersensitivity reaction can develop. Maternal psychological trauma in utero may also be a strong indicator for development of atopy.

The term "atopy" was coined by Coca and Cooke in 1923. Many physicians and scientists use the term "atopy" for any IgE-mediated reaction (even those that are appropriate and proportional to the antigen), but many pediatricians reserve the word "atopy" for a genetically mediated predisposition to an excessive IgE reaction. The term is from Greek ἀτοπία meaning "placelessness".

The most common symptoms of salicylate sensitivity are:

- Stomach pain/upset stomach

- Tinnitus ringing of the ears

- Itchy skin, hives or rashes

- Asthma and other breathing difficulties

- Angioedema

- Headaches

- Swelling of hands, feet, eyelids, face and/or lips

- Bed wetting or urgency to pass water

- Persistent cough

- Changes in skin color/skin discoloration

- Fatigue

- Sore, itchy, puffy or burning eyes

- Sinusitis/Nasal polyps

- Diarrhea

- Nausea

- Hyperactivity

- Memory loss and poor concentration

- Depression

- Pseudoanaphylaxis

Pemphigus vulgaris most commonly presents with oral blisters (buccal and palatine mucosa, especially), but also includes cutaneous blisters. Other mucosal surfaces, the conjunctiva, nose, esophagus, penis, vulva, vagina, cervix, and anus, may also be affected. Flaccid blisters over the skin are frequently seen with sparing of the skin covering the palms and soles.

Blisters commonly erode and leave ulcerated lesions and erosions. A positive Nikolsky sign (induction of blistering in normal skin or at the edge of a blister) is indicative of the disease.

Severe pain with chewing can lead to weight loss and malnutrition.

Pityriasis lichenoides chronica is an uncommon, idiopathic, acquired dermatosis, characterized by evolving groups of erythematous, scaly papules that may persist for months.

Although other forms of the disease occur at younger ages, some individuals start having long term symptoms at thirty years of age. This disease also affects adolescents and young adults. This also affects the immune system which therefore results in rashes. The symptoms rarely affect the face or scalp, but occurs at other sites of the body. The duration may last for months or even several years. For instance, new crops of lesions appear every few weeks.

Some examples:

- Allergic asthma

- Allergic conjunctivitis

- Allergic rhinitis ("hay fever")

- Anaphylaxis

- Angioedema

- Urticaria (hives)

- Eosinophilia

- Penicillin allergy

- Cephalosporin allergy

- Food allergy

- Sweet itch

Farmer's lung (not to be confused with silo-filler's disease) is a hypersensitivity pneumonitis induced by the inhalation of biologic dusts coming from hay dust or mold spores or any other agricultural products. It results in a type III hypersensitivity inflammatory response and can progress to become a chronic condition which is considered potentially dangerous.

Type I hypersensitivity (or immediate hypersensitivity) is an allergic reaction provoked by reexposure to a specific type of antigen referred to as an allergen. Type I is not to be confused with type II, type III, or type IV hypersensitivities, nor is it to be confused with Type I Diabetes or Type I of any other disease or reaction.

Exposure may be by ingestion, inhalation, injection, or direct contact.

Suberosis, also known as corkhandler's disease or corkworker's lung, is a type of hypersensitivity pneumonitis usually caused by the fungus "Penicillium glabrum" (formerly called "Penicillum frequentans") from exposure to moldy cork dust. "Chrysonilia sitophilia", "Aspergillus fumigatus", uncontaminated cork dust, and "Mucor macedo" may also have significant roles in the pathogenesis of the disease.

Aspirin-induced asthma, also termed Samter's triad, Samter's syndrome, aspirin-exacerbated respiratory disease (AERD), and recently by an appointed task force of the European Academy of Allergy and Clinical Immunology/World Allergy Organization (EAACI/WAO) Nonsteroidal anti-inflammatory drugs-exacerbated respiratory disease (N-ERD). is a medical condition initially defined as consisting of three key features: asthma, respiratory symptoms exacerbated by aspirin, and nasal/ethmoidal polyposis; however, the syndrome's symptoms are exacerbated by a large variety of other nonsteroidal anti-inflammatory drugs (NSAIDs) besides aspirin. The symptoms of respiratory reactions in this syndrome are hypersensitivity reactions to NSAIDs rather than the typically described true allergic reactions that trigger other common allergen-induced asthma, rhinitis, or hives. The NSAID-induced reactions do not appear to involve the common mediators of true allergic reactions, immunoglobulin E or T cells. Rather, AERD is a type of NSAID-induced hypersensitivity syndrome. EAACI/WHO classifies the syndrome as one of 5 types of NSAID hypersensitivity or NSAID hypersensitivity reactions.