Will radiation therapy affect my hair?

The honest answer is YES.

Radiation therapy does cause hair loss but the hair loss only occurs on the side that is radiated. Rest assured, you will lose all hair on the side which is radiated. Once the radiation treatments are over, your hair will start to grow back. However, the rate and amount of growth is very variable. 

Most people will get their hair back, but the hair growth will never be 100 % of what it was prior to the radiation. The hair will also vary in texture and fullness. The reason for this is that different individuals receive different amounts of radiation and thus growth rate of hair is also affected. In at least 10-30 percent of people, the hair loss is permanent.

Besides your hair on the scalp, the radiation will also affect adjacent skin. The treated area will initially appear red and look like a sunburn. Moreover, the skin will also feel leathery and dry. So make sure you use adequate moisturizer on your scalp. The skin will also become extra sensitive to both the heat and cold; so make sure your head is adequately protected when you venture outside. If the skin does become irritated and itchy, you can apply a topical steroidal cream. 

Most people wear a wig or a hair piece until the hair loss has recovered- which can take anywhere from 3-9 months after the radiation treatments have stopped.