Allergic rash is also called drug allergic reaction
1. It is an allergic reaction caused by the use of medication. Allergic reactions are an abnormal type of immune response. A normal immune response leads to resistance to the causative agent.
2. There are two necessary factors for the occurrence of allergic rash: allergic constitution and contact with drugs, both of which are indispensable. Allergies are genetically determined and there is no way to change it.
Adverse drug reactions include:
1. drug toxicity.
2.Drug allergy.
3, drug intolerance.
4, drug interactions, etc. People are most familiar with drug poisoning in the past.
The clinical manifestations of allergic rash are diverse and can belong to any type of allergic reaction, and in many cases, it is a combination of multiple types of allergic reactions.
1. Drug fever:The fever caused by an allergic rash is called drug fever. It is often the earliest manifestation of an allergic rash. Drug fever differs from general infectious fever in that it is characterized as follows.
If the drug is administered for the first time, the fever can occur after a sensitization period of about 10 days; if the drug is administered again, the fever can occur rapidly because the body has been sensitized. Drug fever that occurs again is easily associated with drug use because it occurs quickly; whereas drug fever that occurs for the first time is often not considered by patients to be related to the previous drug use because of the long interval, or they simply cannot recall the history of drug use, which makes diagnosis difficult; drug fever is generally a persistent high fever, often reaching 39. C, or even 40. C or more. However, although the fever is high, the patient’s general condition is still good and not proportional to the fever; the application of various antipyretic measures (such as antipyretic drugs) is not effective; but if the allergenic drugs are stopped, sometimes the body temperature can fall on its own even without taking anti-allergic measures.
2, drug rash: allergic rash can often cause a rash, called drug rash. Drug rash usually occurs immediately after drug fever; however, it can also occur before drug fever.
(1) The rash can have a variety of forms, such as measles-like, scarlet fever-like, eczema-like, urticaria-like, purpura-like, herpes-like, etc.
(2) There is a type of fixed drug rash, which is characterized by a rash caused by the same drug, with each episode occurring at the same fixed site. The rash is red at first, then gradually turns dark brown and is difficult to fade, or even does not fade for life. The main drugs that cause this type of rash are phenolphthalein (laxatives), barbiturates (sedatives), sulfonamides, heavy metal salts (such as bismuth, antimony), arsenic, etc.
(3) However, the morphology of most drug rashes is not specific, which means that the allergenic drug cannot be identified based on the morphology of the drug rash.
(3) Serum sickness-like reaction: Serum sickness is an allergic reaction that occurs after about 10 days of the first application of serum (such as horse serum) preparations.
Clinical manifestations include fever, swollen lymph nodes, painful joints, enlarged liver and spleen, etc. The clinical manifestations of serum disease due to the injection of foreign serum are generally mild and often self-limiting. As the serum level decreases, the acute symptoms usually disappear after 3 to 5 days, and other symptoms gradually resolve. Due to the advent of chemotherapeutic agents and antibiotics, the need for serum agents to treat the disease is now limited to a limited number of diseases. However, non-serum-based agents can also cause these clinical manifestations by similar mechanisms, especially synthetic drugs. Therefore, these diseases are also referred to as serum diseases or serum-like reactions.
4. Other systemic damage:
Severe allergic rash reactions can cause systemic damage
1. anaphylaxis.
2, hemocytopenia (hemolytic anemia, granulocytopenia, thrombocytopenia, etc.);
3. Respiratory symptoms (rhinitis, asthma, alveolitis, pulmonary fibrosis, etc.);
4, digestive symptoms (nausea, vomiting, abdominal pain, diarrhea, etc.);
5, liver damage (jaundice, bile depression, liver necrosis, etc.);
6, kidney damage (hematuria, proteinuria, renal failure, etc.);
7, neurological damage (migraine, epilepsy, encephalitis, etc.).