Getting a professional haircut is less dangerous than lowering your head over the stove and pulling it back when the strands sizzle up to the right length. Get a smoking-hot new 'do with this Groupon. Choose from Three Options $19 for a haircut and style (a $45 value) $49 for a cut and color or a cut and partial highlights (a $120 value) $59 for a cut and full highlights or an express keratin straightening treatment (a $145 value) Some hair-straightening products that claim to be formaldehyde-free include aldehyde compounds, which are similar to the carcinogen formaldehyde. Side effects may include nosebleeds, headaches, vomiting, and respiratory problems, among others. Learn more about the health risks here.