Source: Drug Evaluation Center
Urticaria is a limited edema reaction caused by the expansion and permeability of small blood vessels in the skin and mucous membranes. Mast cells are the key effector cells in the pathogenesis of urticaria. The main clinical manifestations are wind masses and/or angioedema, the size and shape of wind masses are different, and it is often accompanied by itching.
First, to cause treatment
(this picture comes from the Internet)
The cause of urticaria can be divided into exogenous and endogenous.
Exogenous causes are mostly transient , such as food, food additives, mosquito bites, traditional Chinese medicine, chemical medicine, and biological products. The endogenous causes of are mostly persistent , such as chronic occult infection, inflammatory bowel disease, rheumatic fever, vitamin D deficiency, fatigue, mental stress, etc.
Note that non-steroidal anti-inflammatory drugs such as aspirin and enalapril and other "pristine" antihypertensive drugs may cause urticaria .
anti-Helicobacter pylori treatment has a certain effect on urticaria associated with Helicobacter pylori-related gastritis.
Some chronic urticaria may be caused by eggs, seafood, smoking, etc. Allergen checks, food diaries, and smoking cessation are effective ways to find allergens.
Urticaria patients generally do not need to stop drinking , but need to abstain from alcohol. The water temperature of bathing is generally controlled below 40℃.
Second, the drug treatment of acute urticaria
For patients with mild to moderate urticaria , the second-generation non-sedating antihistamine is the first choice. When clarifying and removing the cause and when oral antihistamines cannot effectively control symptoms, glucocorticoids can be used.
For severe urticaria patients with laryngeal edema , choose intravenous or intramuscular injection of dexamethasone.
For patients with acute urticaria with shock or severe urticaria with angioedema, , choose 1:1000 adrenaline injection 0.2~0.4ml intramuscular or subcutaneous injection.
Three. Drug treatment of chronic urticaria
Chronic urticaria refers to the daily or intermittent onset of wind masses with a duration of> 6 weeks.
1, first-line treatment
is the first choice for second-generation non-sedating antihistamines (see the table below). After treatment is effective, the dose is gradually reduced to achieve effective control of wind mass as the standard, and the minimum dose is used to maintain treatment.
The course of treatment for chronic urticaria is generally not less than 1 month, and can be extended to 3~6 months or longer if necessary. The first-generation antihistamines of
are effective in the treatment of urticaria, but adverse reactions such as central sedation and anticholinergic effects limit their clinical application, so they are not a first-line choice.
2, second-line treatment
The conventional dose of second-generation antihistamines cannot effectively control symptoms after 1 to 2 weeks of use. Taking into account the differences in the response of different individuals or urticaria types to treatment, can be replaced with antihistamines , Or combined with other second-generation antihistamines to enhance the anti-inflammatory effect, or combined with the first-generation antihistamines to extend the patient’s sleep time before going to bed, or should be taken before the patient’s informed consent. Histamine increases the dose by 2 to 4 times.
3, third-line therapy
patients who do not respond to antihistamine therapy, may consider the following medications.
Tripterygium wilfordii polyglycoside tablets, 1～1.5mg/kg daily, 3 times orally, when using, pay attention to the inhibition of hematopoietic system, liver damage and reproductive toxicity and other adverse reactions.
cyclosporine, 3.5mg/kg per day, orally divided into 2 to 3 times, because of its high incidence of adverse reactions, it is only used for severe patients who are ineffective to any dose of antihistamines.
Omalizumab (anti-IgE monoclonal antibody) has a good effect on most refractory chronic urticaria. It is recommended to be injected subcutaneously at a dose of 150-300 mg, once every 4 weeks.
glucocorticoids are suitable for patients with poor therapeutic effects. Generally recommended oral prednisone 0.3~0.5mg/kg/d, or equivalent doses of other glucocorticoids, gradually reduce the dose after getting better, usually the course of treatment does not exceed 2 weeks.
IV. Drug treatment for special populations
1, children
The first-generation antihistamines have a strong sedative effect, affecting wakefulness and cognitive function, and can only be used as second-line treatment drugs. Promethazine has potentially lethal respiratory depression and is contraindicated for children under 2 years of age.
second-generation antihistamines, also need to pay attention to age restrictions. Most second-generation antihistamine drug instructions suggest that they can only be used in children ≥ 2 years old. "Expert Consensus on the Application of Antihistamines in Dermatology" believes that cetirizine and loratadine are safe for children> 6 months.
When the conventional dose treatment is ineffective, with the informed consent of the patient’s guardian, can increase the dose of the second-generation antihistamine as appropriate, which needs to be adjusted according to body weight.
2, the elderly
The elderly prefer to use second-generation antihistamines to avoid the central inhibitory and anticholinergic effects that may be caused by the first-generation antihistamines, and to prevent the risk of falls and adverse reactions such as glaucoma and dysuria .
3, pregnant women
In principle, antihistamines should be avoided as much as possible during pregnancy.
If antihistamine treatment is necessary, patients should be informed that there is no absolutely safe and reliable drug. In the case of weighing the pros and cons, can choose relatively safe and reliable second-generation antihistamines, such as loratadine, cetirizine and levocetirizine.
4, lactating women
all antihistamines may be secreted by breast milk.
The second-generation antihistamines without sedation are also preferred during lactation. Because first-generation antihistamines may cause reactions such as decreased appetite and lethargy in infants, they should be avoided.
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