Some causes of red blotches on the lower legs are psoriasis, allergies, infections, eczema and Schamberg's disease, states Healthline. The most common cause of red blotches is eczema, which is a common rash for people suffering from asthma or have allergic reactions.
Psoriasis is a condition in which a person's skin cells grow faster than normal, according to Webmd. The red blotches are usually accompanied by pain and swelling. Different types of allergic reactions, such as ones caused by insect bites or cosmetics, can also cause red blotches to appear on a person's lower legs. Some ingredients in cosmetic products such as lotions can trigger the red blotches. Bacterial infections can cause red blotches to appear on the skin and usually require medication.
Schamberg's disease is characterized by reddish spots and itching, and occurs when leaky blood vessel walls allow blood to seep through into the skin, notes Skin Site. There is no cure for Schamberg's disease, but vitamin C supplements help provide relief. Red blotches on a person's lower legs are usually treated by washing the affected area with warm water and soap. Avoiding scratching the red blotches also prevents aggravation of the redness, and over-the-counter lotions such as hydrocortisone cream can help to relieve the pain.