Poison can show up on weapons; on darts, needles, or spikes in traps; in food or drink offered by a treacherous foe; and anywhere else you did not expect it. Human foes are not the only ones who can poison you. Snakes, insects, and certain other creatures have natural poison (usually blood agents) – and eating the wrong plant or animal may treat you to a dose of digestive poison.

DESCRIBING POISONS

A poison’s description includes its name, means of delivery, delay, resist- ance roll, effects (injury and symptoms), and cost per dose – and possibly notes on what constitutes a “dose,” how to use or conceal the poison, and how to treat it (including any antidotes).

A poison can have multiple sets of effects. For example, tear gas is both a respiratory agent (with one set of effects) and a vision-based agent (with other effects)

DELIVERY

A given poison might reach its victim in any of several ways:

• Blood Agent: The poison must reach a mucous membrane (eyes, open mouth, nose, etc.) or an open wound. If it is sprayed or spat, it must actually strike one of these vulnerable areas (so a spitting cobra must target the face). If it is delivered as a gas or wide-area spray, only those with the Sealed advantage (p. 82) – or with one of Doesn’t Breathe (p. 49) or Filter Lungs (p. 55) and one of Nictitating Membrane (p. 71) or Protected Vision (p. 78) – are immune. These advantages might be natural or provided by equipment.
• Contact Agent: The poison must be inhaled or touch skin to take effect. If it is use to poison a melee weapon, the weapon must hit an unarmored and unclad hit location for the poison to affect the target. If it is delivered as a gas or wide-area spray, it affects everyone in the area who lacks the Sealed advantage (whether natural or provided by a suit, vehicle, etc.).
• Digestive Agent: The victim must swallow the poison. This is typical of poisonous plants and toxic substances such as arsenic. If the poison has a slight but distinctive taste (e.g., cyanide), the GM can allow the victim a Taste roll or Perception-based Poisons roll – at a basic -2, but +2 per doubling of dosage – to notice it in time. Poisons that are easier to detect give a bonus; those that are harder to detect, or whose taste is masked by suitable food or drink, give a penalty. To force someone to swallow a poison rather than spit it out, you must grapple him by the head or neck and maintain your hold for 10 seconds.
• Follow-Up Poison: The poison must be placed on a piercing or impaling weapon, or injected using a hollow projectile, hypodermic needle, etc. If the weapon penetrates DR and does any damage, it delivers the poison. Most “follow-up” poisons are simply blood or contact agents injected into the body.
• Respiratory Agent: The poison is a gas that only affects those who inhale it into their lungs. Delivery is usually via an area or cone attack (e.g., gas grenade, spray gun, or dragon’s breath), but an entire atmosphere could be poisonous! Only Doesn’t Breathe and Filter Lungs protect completely against respiratory agents – but a victim who makes a Sense roll to notice the poison in time may hold his breath (see Holding Your Breath, p. 351). Unconscious or stunned victims inhale automatically. An improvised mask, such as a wet towel over the face, gives +1 to HT to resist.
• Sense-Based Agent: The poison affects the victim through a specific sense. It has no effect on those who lack that sense or have appropriate protection. A smell-based agent is usually a foul stench that induces nausea; suitable protection is nose plugs, a respirator, or the Protected Sense (Smell) advantage. A vision-based agent is generally a cloud of gas that irritates the eyes; appropriate protection is a gas mask, goggles, or the Protected Sense (Vision) advantage. See Sense-Based (p. 109).

DELAY

Most poisons require a few seconds to several hours to take effect. This is nearly always true for digestive agents.

Delays given are for victims with Size Modifier 0. The victim’s size modifies delay: each +1 to SM doubles the delay; each -1 to SM halves the delay. For example, if the delay is 1 hour, someone with SM -2 is affected in only 15 minutes.

RESISTANCE ROLL

Some poisons give the victim a HT roll to resist. Make this roll after the delay, if any, has passed. There is often a modifier: a mild poison might call for a HT+2 roll, while one that is almost impossible to resist might require a HT-8 roll! HT to HT-4 is typical. DR never affects this roll.

If you’re in a poisonous environment (like a gas cloud or toxic atmosphere) and make your initial HT roll, you must roll again once per second until the poison affects you or you leave the area. If the poison has a delay, roll after each delay period instead.

Some poisons are specific to certain species and do not affect others. Others are easier or harder for particular species to resist. These effects are up to the GM.

EFFECTS OF POISON

The most common effect of poison is toxic or fatigue damage. Mild poisons might only inflict 1 HP or FP; more severe poisons might inflict 1d or more. DR has no effect on this damage. These HP and FP losses heal normally, but if the poison is cyclic (see below), no healing is possible until after the final cycle!

Damaging poisons sometimes affect their victims gradually, causing damage each time a specified interval of time passes. The description of such a poison specifies the length of this interval and the total number of cycles. The interval may vary from one second (for a fast-acting agent) to one day (for a slow poison). The total number of cycles may be two to several dozen.

If a resistible poison is cyclic, the victim gets a new HT roll to resist every cycle. On a success, he shakes off the poison; on a failure, an additional cycle of damage occurs. Note that even a poison that inflicts 1 HP of injury per day can be lethal if it’s hard to resist and lasts for two dozen cycles!

A poison always has some symptoms. The basic damage includes symptoms such as swelling, headache, and fever. Poisons that inflict toxic damage may have more severe symp- toms that occur automatically after the poison causes enough injury (usually 1/3, 1/2, or 2/3 of the victim’s HP). For example, a poison might result in blindness once the victim loses 1/2 his HP. Symptoms vanish when the victim’s HP rise above this threshold.

Some poisons cause effects other than injury or fatigue, including attribute penalties, irritating or incapacitating conditions (see Afflictions, p. 428), temporary disadvantages, or even the removal of existing advantages (e.g., an alchemical poison that negates Magery). The victim usually gets a resistance roll against these effects, and the effects always have a specific duration. The default duration is a number of minutes equal to the margin of failure on the resistance roll. In a poisonous environment, a failed resistance roll means the effects last for as long as you’re in the environment plus the duration.

COST PER DOSE

It is up to the GM whether a particular poison is for sale - it might be impossible to extract in a useful form, or the authorities might want to keep it off the market. If a poison is available, its cost often reflects how difficult it is to obtain, not its effectiveness. In most game worlds, people who sell poisons are criminals. All of these factors make cost per dose highly variable. See Poison Examples (p. 439) for suggestions . . . but the GM is free to use whatever prices he feels are reasonable.

DOSAGE

The statistics given in a poison’s description always assume one “dose”: enough poison to produce the described effects in one victim. Some additional notes:

• Contact Agents: One dose of a contact agent coats or affects a single hit location.
• Gases and Sprays: One dose of a respiratory agent, or a blood or contact agent in gas or spray form, affects one hit location on one victim. For a respiratory agent, this must be the face. Ten doses are enough to affect everyone in a room (say, a 2-yard radius).
• Poisoned Weapons: One dose of a follow-up poison envenoms the tip of a piercing or impaling weapon, or fills a hypo. Poisoning the edge of a weapon, so that a cutting attack can deliver it, requires three doses per yard of reach. Most poisons on blades only last for one successful strike or three blocked or parried ones. Misses and dodged attacks do not rub off the poison.
• Varying the Dosage: It is possible to vary the dosage of a digestive agent or a follow-up poison delivered by hypo- dermic. Each doubling of dosage (and cost!) halves the delay and interval, doubles damage, gives -2 to HT rolls to resist, and gives +2 to all rolls to detect the poison (including the victim’s Sense rolls, and any Diagnosis or Forensics roll made to investigate the victim’s symptoms or death). Using less than one full dose may reverse these modifiers or simply make the poison ineffective, at the GM’s option.

TREATMENT

If the poison has a delay, there may be time to treat the victim before he suffers any ill effects. Since he will not yet be showing symptoms, he must be aware of his predicament in order to seek help!

A poisonous animal bite is usually obvious – but the GM may require a Naturalist roll to realize that an animal is venomous. Sucking the poison from the wound takes a minute, requires a First Aid or Physician roll at -2, and gives +2 on HT rolls to resist.

If the victim suspects a digestive agent, he or a friend can induce vomiting to expel the poison. This takes 10 seconds, calls for a First Aid or Physician roll, and gives +2 to resist the poison. But for some poisons, vomiting is a bad idea – it can increase injury!

It might also be possible to take an antidote. Antidotes exist for only a few poisons. Where they do exist, they are usually specific to the poison. The correct antidote gives the victim a bonus to HT rolls to resist the poison, or even completely halts the poison.

Medical procedures – chelation, gastric lavage, intravenous fluids, oxygenation, etc. – can also give a HT bonus, but only if the treatment suits the poison. Such measures require a Physician roll. The HT bonus never exceeds TL/2 (round up, minimum +1).

To learn whether it is safe to induce vomiting, or which antidotes or procedures to use, you must identify the poison. This is tricky before symptoms appear! The GM may require rolls against Poisons (to identify a residue on a dart, in a glass, etc.), Naturalist (to identify a venomous animal), or even Intimidation (to force the poisoner to reveal what he used).

Once the victim takes damage, symptoms appear. At this point, a Diagnosis or Poisons roll can identify the poison. If the poison is cyclic, the correct antidote or medical procedures can help prevent further damage, providing their bonus to future HT rolls.

Source: GURPS 4th - Basic Set - Combined, page 441