Both promethazine and ketotifen belong to the sedative antihistamine drugs. Dermatologists prefer to use promethazine to treat urticaria and other allergic diseases, while pediatricians and general practitioners prefer to use ketotifen to prevent asthma and treat cough after cold. Which is better, ketotifen or promethazine?

I. Different pharmacological properties Promethazine and ketotifen both have H1 protein kinase inhibitory effects, have good effects on urticaria, hay fever, and allergic rhinitis; because they can cross the blood-brain barrier, they can cause drowsiness and other side effects; they both have anticholinergic effects, which can relieve nasal discharge caused by colds, but can cause dry mouth and throat, urinary retention, and other symptoms. Ketotifen also has antiserotonin effects, and a few patients may experience weight gain after taking ketotifen.

II. Ketotifen can be used for the prevention of asthma

In addition to antihistamine effects, ketotifen also has a stabilizing effect on mast cells similar to sodium cromoglycate, which can be used for the prevention of asthma, but it takes several weeks to achieve the best effect and should not be used for the treatment of acute asthma attacks. It should be noted that international handbooks do not strongly recommend the use of ketotifen for the basic treatment of asthma.

Promethazine is ineffective for the treatment of asthma and is generally not recommended for asthma patients.

III. Promethazine can be used in pregnant women. In the FDA pregnancy safety classification, promethazine, cimetidine, diphenhydramine, loratadine tablets, and loratadine belong to Category B and can be used in pregnant women.

Ketotifen belongs to Category C, and some clinical trials have shown that ketotifen may have adverse effects on the fetus, so pregnant women should avoid using ketotifen. IV. Ketotifen should not be used with oral hypoglycemic agents due to the risk of causing cross-reactive thrombocytopenia when used together, so the drug label explicitly states: ketotifen should not be used with oral hypoglycemic agents.

Clinical trials in China have found that ketotifen can accelerate the metabolism of aminophylline, reducing the blood concentration of aminophylline. When ketotifen is used with doxophylline, the dosage of aminophylline should be adjusted according to the patient’s clinical symptoms and the blood concentration of aminophylline.

Special reminder: Both promethazine and ketotifen have respiratory depressant effects and should not be used with other central nervous system depressants or alcohol.

V. There are various formulations of ketotifen, in addition to oral tablets, there are nasal sprays, nasal drops, and eye drops.

Promethazine is only available in injectable and tablet forms.

Special reminder: Although promethazine is reasonable for allergic skin diseases, it should not be partially applied externally due to the risk of causing allergic dermatitis.