Scalp is itchy red and swollen how do I treat my scalp?

How long? If this just started, think about anything that you have recently changed, such as your shampoo, hair dye, etc., etc. If it is a chronic problem it could be psoriasis, severe seborrheic dermatitis, or even a scalp infection. Scalps with significant redness & swelling do not usually respond to otc treatment; i would suggest that you see a dermatologist.