Swelling of the little thumb by mosquito bites belongs to the allergic reaction caused by insect bites, which can be treated with oral medication or topical medication. 1. Oral medication: the first generation of antihistamines can be used, such as Benadryl; or the second generation of antihistamines, such as cetirizine, loratadine, etc.. 2. Topical ointment: If the bite wound is infected, antibiotic ointment (e.g., Mupirocin) should be applied at the same time; if the degree of swelling is more serious or the pain is obvious, glucocorticoid ointment can be given to anti-inflammatory. If the little thumb is mosquito bite swelling symptoms are serious, should promptly seek medical attention, drugs need to be used under the guidance of a doctor.