This is a proposed set of healing and herb rules for D20 Resident Evil. It is currently a work in progress.
Unless stated otherwise, Treat Injury works identically to the rules in the d20 Modern core rulebook. Characters can have hit points restored once per day with the use of a medical kit and can even undergo surgery (a rather difficult proposition, however, due to the length of time the other heroes have to fend off the B.O.W.s in a dirty room) exactly as described in the core rulebook.
However, the characters can also use herbs to assist in their healing.
A green herb heals 1d6 + 1 hit point per level. Special abilities that increase hit point healing, such as Healing Touch and the Field Medic abilities add to the damage healed. A successful Treat Injury check (DC 20) increases the amount of healing to double the usual amount.
Green herbs can be mixed with the red herb to create a super strength healing mixture, which doubles the amount of healing (note that two doublings result in a tripling). If the hero that mixes the herbs makes a successful Craft (pharmaceutical) skill check DC 25, the amount of healing is "doubled" again. Finally, a successful Treat Injury check (DC 20) once again "doubles" the amount of healing. In total, a mixed herb created and applied by a competent medic, such as Rebecca Chambers, can heal 5d6 + 5 hit points per level, and perhaps a few more hit points from class abilities.
As a result, herbs should be rare. The party should not have access to more than one green herb per PC at any one time. The herbs are so rare they would only be stockpiled in hospitals (which, of course, have a bad tendency of being filled with recently infected victims, now zombies, plus crawl with Umbrella troops).
Homeostatic capsules can prevent bleeding just like a first-aid kit. (They're almost useless if you already have a medical kit.)
Antidote: Grants a second save throw to resist the effects of poison or counteracting poisons, with a +2 on the save.
Serum: Grants a second save throw to resist the effects of poison or counteracting poisons, with a +5 bonus to the save.