Itchy red bumps on the thighs may be caused by mosquito bites, contact dermatitis, eczema, ringworm and other causes. 1. Mosquito bites: thigh area by mosquito bites will appear localized skin red bumps, and accompanied by itching discomfort. 2. contact dermatitis: thigh skin contact with external sensitizers or irritants lead to inflammatory reactions, resulting in local skin red bumps, pimples, itching and other discomforts, there will be red bumps on the thighs and itchy situation. 3. Eczema: an inflammatory disease caused by internal and external stimuli. Eczema lesions manifested as localized papules, pimples, etc., the patient will also appear thigh red bumps, and accompanied by itching discomfort. 4. Ringworm: an infectious disease caused by skin infection with dermatophytes, mainly manifested as ring-shaped erythema, papules, flaking, itching and other symptoms. It can also lead to itchy red bumps on the thighs. Patients with itchy red bumps on the thighs should pay attention to maintaining local hygiene, avoid scratching the skin, resulting in skin ulceration. If the itchiness can not be relieved in time, it is recommended to go to the hospital in time to avoid the adverse effects of self-medication.