General Meanings:

Bloodletting can warn about approaching quarrels or material losses. Sometimes the loss of a people through separation or death is behind it.

Traditional Meanings:

European (Judeo-Christian)

• Disease if see blood-letting of other person – in the dream you see bleeding of other person, it is a sign of an accident, death or illness;
• Worries and Quarrel if bleeding from veins – You are dreaming that you are bleeding from veins, this means strife, infirmity, mental suffering, annoyance, misfortune.

Hindu (Hinduism)

• Losses if see other bleeding – Dreaming of bleeding from an unknown person, means that you will lose your money and property depending on the quantity of blood;
• Happiness if bloodletting from an old man – This dream announces about your destiny, it means that you stand under the lucky star;
• Expenses if let blood because of illness or to cure - According to the blood loss you will have  money spending, but you will have incomes for life and health;
• Award if someone lets blood of a friend – This dream announces that you will be awarded because of your hard work;

Arabian (Islamic)

You must know that like the hair and the blood of man means power and wealth, it refers only to a much greater degree of wealth. 

• Profit if bleeding from head – In your dream blood runs from your head, so the flowing blood means profit and abundance of your leadership;
• wealth if discover blood – You are dreaming that you discover blood and use it for any purpose, you will acquire foreign wealth according to its quantity.

* Please, see meaning of blood.