well yeah, its bad. its kind of mixed though, i think the pros of using a blowdryer way outweigh the cons so ill tell you here:
pros- my hair feels lighter, softer, and never gets tangled or frizzy if i blowdry.
cons- if you blowdry wrong, it will get frizzy. and my sisters say it kills your hair but hair is already dead. and it may dull the color if you have color treated hair but for that you should just deep condition once a week or use some amazing shampoo and conditioner by pureology for instance.
i use my blowdryer about 5-7 days a week. meaning i use it everyday and at the least, 5 days. my hair looks best when i blowdry, its that simple.
yea its bad for the hair if you use it too much. Which is the reason I air dry my hair often. Buuttt, like mutti said there are certain blow dryers that are more expensive but worth the money I think if you want something less damaging on the hair. Starlite is also right w/ the pros and cons. It does make hair more manageable unless you flatiron it so...
sprays w/ heat protectors often leave a film on the hair or make it hard since most of em are in the form of a hairspray but they still help. Rangerkays recommendation on specially formulated shampoos and conditioners are good also.
The sun is just as damaging on hair so try to protect it from the sun!