Narcotic Analgesics	Inhalants	Cannabis
Action	All narcotic analgesics share three important characteristics: they will relieve pain, they will produce withdrawal symptoms when the drug is stopped after chronic administration, and they will suppress the withdrawal signs and symptoms of chronic morphine administration.	Some inhalants include psycho-active chemicals that produce a variety of effects.  Others exert their major effect by blocking the passage of oxygen to the brain.	Marijuana and other Cannabis products apparently impair the attention process.  Ability to perform divided attention tasks diminishes under the influence of Cannabis.
General Indicators	"On the nod," droopy eyelids, depressed reflexes, dry mouth, facial itching, low raspy speech, fresh puncture marks may be evident.	Disorientation, confusion, slurred speech, possible nausea, possible residue of substance on face, hands, clothing.	Very bloodshot eyes, body tremors, odor of marijuana, disoriented, relaxed inhibitions, difficulty in dividing attention.
Eye Indicators
Nystagmus - horizontal	Usually not present	Usually present	Usually not present
Nystagmus - vertical	Usually not present	May be present	Usually not present
Pupil size	Usually severely restricted	Usually normal	Near normal or possibly slightly dilated

	Depressants	Stimulants
Action	Slow down the operations of the brain.  Depress the heart rate, blood pressure, respiration and many other processes controlled by the brain.	Accelerate the heart rate and respiration, elevate the blood pressure and "speed up" or over-stimulate many other processes of the body
General Indicators	"Drunken" behavior, uncoordinated, drowsy, sluggish, disoriented, thick, slurred speech.	Restlessness, talkative, excitation, euphoria, exaggerated reflexes, loss of appetite, grinding teeth (Bruxism), redness to nasal area (if "snorting"), body tremors.
Eye Indicators
Nystagmus - horizontal	Usually present	Usually not present
Nystagmus - vertical	May be present	Usually not present
Pupil size	Usually normal (Except that the drug Methaqualine causes pupils to dilate)	Usually noticeably dilated
	Hallucinogens	PCP
Action	Cause hallucinations. i.e. they cause the user to perceive things differently from the way they really are.	Powerful anesthetic. It also causes bizarre and sometimes violent behavior.
General Indicators	Hallucinations, dazed appearance, body tremors, uncoordinated, perspiring, disorientation, paranoia, difficulty in speech, nausea.	Perspiring, repetitive speech, confused, possibly violent and combative, blank stare, incomplete verbal responses, muscle rigidity.
Eye Indicators
Nystagmus - horizontal	Usually not present	Usually present, with very early onset and very distinct jerking.
Nystagmus - vertical	Usually not present	Usually present
Pupil size	Usually noticeably dilated	Usually normal