Bug bites swollen a large piece is the emergence of insect bite dermatitis, need to be improved through medication, physical therapy methods. 1. medication: insect bite dermatitis is mosquito bites the skin after the local injection of saliva, resulting in an allergic reaction to the skin. You can follow the doctor’s instructions to apply local hydrocortisone butyrate cream, mometasone furoate cream and other drugs, can play an anti-inflammatory, anti-itching and anti-allergic effect, if there is obvious itching, you can also take cetirizine hydrochloride tablets, loratadine tablets and so on. 2. Physical therapy: If the bug bite is swollen with a large piece of physical therapy can also be used with the use of ice towels or ice packs on the local ice packs, can promote subcutaneous capillary contraction, play a role in reducing swelling, for the relief of itching and pain also has a certain effect. Bug bites swollen a large piece of the need to pay attention to skin care, avoid scratching or rubbing, so as to avoid skin breakage caused by infection. These medications should be used under medical supervision.