Hives, also known as urticaria, are the most common type of drug allergy. They are characterized by raised, itchy, red welts on the skin.

Penicillins are the drug class most commonly associated with anaphylaxis, a severe and potentially life-threatening allergic reaction.

Immediate hypersensitivity reactions are mediated by the release of histamine and other mediators from mast cells and basophils upon exposure to an allergen.

Type III hypersensitivity reactions are characterized by the formation of immune complexes, which can activate complement and lead to tissue damage.

Contact dermatitis is the most common type of delayed hypersensitivity reaction. It is caused by direct contact with an allergen, such as poison ivy or nickel.

Skin prick test is the most commonly used test to diagnose penicillin allergy. It involves pricking the skin with a needle containing a small amount of penicillin and observing for a reaction.

Epinephrine is the first-line treatment for anaphylaxis. It is a potent vasoconstrictor and bronchodilator that can help to reverse the symptoms of anaphylaxis.

Cephalosporins are the drug class most commonly used to prevent allergic reactions to penicillin. They are structurally similar to penicillin, but they are less likely to cause allergic reactions.

The recommended duration of desensitization therapy for penicillin allergy is 8 hours. This involves gradually increasing the dose of penicillin over a period of time until the patient can tolerate the full dose without an allergic reaction.

Type II hypersensitivity reactions are characterized by the activation of cytotoxic T cells, which can directly kill target cells.

Acetaminophen is the most common cause of drug-induced liver injury. It can cause liver damage if taken in high doses or for a long period of time.

Sulfonamides are the drug class most commonly associated with Stevens-Johnson syndrome and toxic epidermal necrolysis, which are severe and potentially life-threatening skin reactions.

Antithyroid drugs, such as propylthiouracil and methimazole, are the most common cause of drug-induced agranulocytosis, a condition characterized by a severe decrease in the number of neutrophils.

Chloramphenicol is the drug class most commonly associated with aplastic anemia, a condition characterized by a severe decrease in the production of all blood cells.

Quinine is the most common cause of drug-induced hemolytic anemia, a condition characterized by the destruction of red blood cells.