Can restoration be used as a main damage spell? Like instead of destruction, you choose restoration to damage. I think restoration has a drain health spell right?

No it doesn't include drain health spell.
http://www.uesp.net/wiki/Skyrim:Restoration#Spells

You can use some of the undead damaging spells, but even against the undead, destruction spells would do far more damage.

Unless you're using Stendarr's Aura AND Sword and Boarding a Paladin.

Wrong game unfortunately. Oblivion had Absorb Health, which was a restoration spell (and a darn powerful one). In Skyrim, only vampires have it. Unless you mod the game to make it into a regular spell.

As others have said, no. Restoration is still a good school of magic though, i usually use it in every build. Great healing abilities + stamina healing perk + magika regen perk.

Hmmm now that i think about it, i think im going invest even more in restoration on my current character.

Yeah there is no drain health but restoration is very helpful.

Cheers

And just for further clarification, there is a life drain spell of sorts in Skyrim, Equilibrium, which works only on the caster, and converts HP to MP, but is an Alteration spell IIRC.