Chlorpheniramine, also known as chlorpheniramine, is the main component of compound cold medicines and is used by a wide range of people, including children, the elderly, and patients with underlying diseases. Domestic drug instructions stipulate that neonates and premature infants should not use chlorpheniramine; foreign countries recommend not to use compound cold medicines (over-the-counter medicines) for children under 6 years old. Warm reminder: Forget the following two points, chlorpheniramine can be fatal!
1. Forgot to ask before doing the skin test: Have you taken any cold medicine?
Use a case to speak.
Patient, female, 27 years old. Due to throat pain, fever, body temperature of 38.5 ℃, cough, general fatigue and weakness, I took compound phenol coffee pseudoma capsules and vitamin C Yinqiao tablets by myself. Because the effect was not good, penicillin was given intravenously in the hospital.
Before medication, use a standard concentration skin test solution and perform a penicillin skin allergy test according to strict operating procedures. After 20 minutes of observation, if there is no local or systemic reaction, add 8 million μ of penicillin to 250 ml of normal saline for intravenous infusion.
5 minutes after the intravenous infusion of penicillin, the patient developed symptoms such as nausea, vomiting, dizziness, palpitations, pale complexion, chest tightness, and coughing up pink foamy sputum. His blood pressure was 75/50mmHg. Consider penicillin anaphylactic shock and give epinephrine immediately. After 30 minutes of rescue, the patient was in danger.
Special reminder:
Many families have compound cold medicines. Many patients take cold medicines by themselves, and many patients also go to the hospital for infusions. Most compound cold medicines contain chlorpheniramine, such as the compound phenolcafe pseudoma capsules and vitamin C Yinqiao tablets in this case. Chlorpheniramine can make skin test results falsely negative. Don’t forget to ask before taking a skin test: “Have you ever used compound cold medicine?”
Chlorpheniramine varies greatly among individuals, with a half-life of 3 to 24 hours. This type of drug needs to be fully discontinued before doing a skin test.
2. Forgot to ask when prescribing: Do you have a history of epilepsy?
The first generation of antihistamines has a small molecular weight, high fat solubility, and easily penetrates the blood-brain barrier. It can both inhibit and excite the central nervous system. Chlorpheniramine has the weakest sedative-hypnotic effect (see table below). For some patients, especially children or the elderly, regular doses can cause mental excitement, insomnia, myotremors, etc.
Chlorpheniramine can induce epilepsy. Patients with a history of epilepsy should use chlorpheniramine with caution. Second-generation antihistamines can be used: cetirizine, levocetirizine, loratadine, and dechlorpheniramine. Raytadine, etc. (not easy to penetrate the blood-brain barrier).
Patient, female, 46 years old. He had a history of urticaria and was taking 4 mg of chlorpheniramine 2 to 3 times a day for a long time. While taking the medicine, the patient had three major epileptic seizures: sudden loss of consciousness, fainting on the ground, twitching of limbs, and foaming at the mouth. After stopping chlorpheniramine under the doctor’s advice, there was no recurrence of epilepsy.
Special reminder:
Although people have always believed that antihistamines can be used to treat colds, in fact, antihistamines are of no value in fighting colds. First-generation antihistamines have weak anticholinergic effects and can reduce symptoms of runny nose, but their drying effects may cause more harm than good.
The first-generation antihistamines can not only cause side effects such as sedation and drowsiness, but also reduce attention, learning ability and memory ability. It can also cause adverse reactions such as dry mouth, nausea, vomiting, constipation, difficulty urinating, and bradycardia.
[1] Chlorpheniramine has the weakest sedative effect; [2] Diphenhydramine and promethazine can be used for motion sickness, radiation sickness, nausea and vomiting caused by surgery and drugs; [3] Diphenhydramine Lamin can be used to fight Parkinson’s disease and drug-induced extrapyramidal symptoms; [4] Cyproheptadine can stimulate appetite and increase weight.
Main references
[1] Zhou Zaixia, Xu Fangfang. A case of immediate anaphylactic shock due to negative penicillin skin test [J]. Medical Theory and Practice, 2009, 22(7): 868
[2] Liu Yan, Zeng Weisheng, Jiang Renchao. A case of epilepsy caused by long-term use of chlorpheniramine [J]. International Medical and Health Herald, 2002, 73 (4): 87
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