Your blood, while completely harmless to you, becomes poisonous to others. Any creature who hits you with a melee or physical touch attack after you’ve already been hit with a piercing or slashing weapon (or have otherwise suffered an open, bleeding wound), or any creature who ingests your blood (such as stirges and leeches), must make a Fortitude save or be poisoned. The magical poison deals 1d3 points of both Strength and Constitution damage.
Creatures that ingest your blood but are immune to poison, such as vampires, will find your blood unpalatable and will not gain the benefits they normally would from drinking healthy blood. A vampire will thus cease draining your blood. Other creatures immune to poison take no damage from your blood splashing on them.