Will a Muslim who donates blood be rewarded for it? And will it be considered charity for him?

Donating blood is a commendable act, and its doer is greatly rewarded, for it is an act of benevolence towards people and alleviating their distress. Evidence for this includes proofs from the Holy Quran and the Prophetic Sunnah, among them:

Allah Almighty says: ﴿وَأَحْسِنُوا إِنَّ اللَّهَ يُحِبُّ الْمُحْسِنِينَ﴾ (And do good; indeed, Allah loves the doers of good). And Allah Almighty says regarding saving a life: ﴿وَمَنْ أَحْيَاهَا فَكَأَنَّمَا أَحْيَا النَّاسَ جَمِيعًا﴾ (And whoever saves a life - it is as though he had saved all mankind). The Hadith: "And whoever is in the need of his brother, Allah will be in his need. And whoever relieves a Muslim of a distress, Allah will relieve him of a distress from the distresses of the Day of Resurrection." The Hadith: "In every wet liver (living creature) there is a reward." The Hadith: "Every good deed is a charity."

If donating blood does not affect the donor's health, and it is for saving an inviolable life and there is no other alternative, then it becomes obligatory, and the reward for an obligatory act is greater than the reward for a supererogatory one.