A lot of bumps on the inner thighs after soaking in a hot spring may be caused by contact dermatitis, urticaria, etc. The treatment is to avoid contact with the irritant immediately, and to use mainly antihistamine or glucocorticoid medication. 1. Contact dermatitis: Inflammatory reaction at the site of skin contact that occurs after contact with a substance in the hot spring water. Leave the hot spring water immediately and use topical glucocorticoids such as hydrocortisone butyrate cream. Antihistamines such as loratadine can be used when itching is pronounced. In severe cases, oral glucocorticoid treatment is required. 2. Urticaria: The induced urticaria caused by certain substances in the hot spring water needs to leave the hot spring immediately. Topical glycerine lotion can be used, and antihistamine drugs such as cetirizine can be taken orally. Anaphylaxis requires systematic application of glucocorticoids and other medications. The appearance of red bumps after bathing in hot springs, do not self-medication, need to seek medical treatment as soon as possible to avoid serious complications.