When looking for a shampoo to straighten out curly or wavy hair, look for the shampoo to contain silicones and polymers. The silicones and polymers, such as dimethicone or cyclomethicone, make the hair slippery and shiny, and work to pull the curl or wave straight. Also look for a humectant conditioner, which moisturizes the hair and weighs the hair down, preventing frizzing and curling.

Any rinse-out product such as shampoo cannot completely straighten hair. A straightening shampoo, however, will increase the straightness of the hair and make the hair easier to straighten by blowing out or using a straightening iron.

Straightening shampoos can be purchased from any drugstore, supermarket, salon or beauty supply store. Straightening shampoos can even be purchased from home shopping channels and online. Target, Sally Beauty Supply and Folica.com are all reputable sources to purchase straightening hair-care products.

Straightening shampoos vary in cost depending on whether they are drugstore brand or salon brand. As of 2010, drugstore brand straightening shampoos range in cost between $8 and $14. Salon and designer brands are more pricey, ranging from $15 to $30. Just because a shampoo is more expensive does not necessarily mean it is the best option.

Regular cleansing shampoos are also available in the same price range as straightening or smoothing shampoos, but will not provide the smoothness and straightening effect of a straightening shampoo.

A moisturizing or smoothing conditioner should be used in conjunction with a straightening shampoo. Conditioners will be available anywhere you can buy shampoo and will cost between $8 and $30.

Try different types of straightening shampoos to find the best fit for your hair type.