How about this:
SKILL CHALLENGE: POISON
At the DM's option, any poison-based attack can have an an aftereffect. Every character who was hit by the poison-based attack is subject to this aftereffect after the encounter ends. The level of the skill challenge is usually equal to the level of the monster or trap whose attack triggered it. The DM must decide what type the poison is and how quickly it acts (fast-acting, normal, or slow-acting).
Victims cannot recover healing surges as long as this skill challenge continues.
Complexity: 2 (6 successes/3 failures)
PRIMARY SKILLS: Endurance, Heal, Nature, History
Endurance (moderate DCs): Once per minute (fast-acting poisons), once per hour (normal poisons), or once per day (slow-acting poisons), the poison victim must spend a healing surge and make an Endurance check to withstand the poison. Only failures on these checks count toward failing the challenge. If the victim has no more healing surges left, she fails automatically.
Heal (moderate DCs): Another character can make a Heal check to purge the poison. Failure costs the victim a healing surge.
Nature (moderate DCs): A character can make a Nature check to recollect some detail of the poison which can aid a healer. On a successful check, the difficulty of Heal checks is reduced to easy. This can only be attempted once.
History (hard DCs): A character can recollect an instance of an important personage being subject to this poison and what was done to treat it. On a successful check, the difficulty of Heal checks is reduced to easy. This can only be attempted once.
SUCCESS: The victim recovers from the poison with no significant ill effects.
FAILURE: The victim suffers one of the following effects:
Weakening Poison: The victim is weakened for 1 day. Every day, she can make an Endurance check at moderate DC, and one other character can attempt a Heal check at moderate DC. Success on either check results in recovery.
Hallucinogenic Poison: The victim is dazed for 1 day. Every day, she can make an Endurance check at moderate DC, and one other character can attempt a Heal check at moderate DC. Success on either check results in recovery.
Paralytic Poison: The victim is paralyzed for 1 hour. Every hour, she can make an Endurance check at moderate DC, and one other character can attempt a Heal check at moderate DC. Success on either check results in recovery.
Lethal Poison: The victim dies.