as in illegal drugs? or prescribed medications?
normally if they seem to be intoxicated they will be given a drug screen in the ER upon admission. so just check their labs. some things to look out for:
heroin/opiates: will be drowsy, maybe hard to arouse, slurred speech, nodding in and out of conciousness, dilated pupils.. if it is wearing off they will be irritable, shaky, n/v, pain everywhere..
cocaine/meth/other stimulants: shaking, talking fast, rapid hr, inability to sit still, inability to stay on topic (rambling), constricted pupils-- coming off, they may be irritable, violent
ecstasy: overly happy, sexually inappropriate, teeth grinding, thirsty, dilated pupils
hallucinigenics (lsd/shrooms): seeing/hearing things that arent there, just acting plain weird, dilated pupils
marijuana: glazed over, puffy eyes, slow reaction, laughing inappropriately, dry mouth, hungry
alcohol: well, i assume youve seen a drunk person before. and they usually smell like booze.
*just because someone is exhibiting some of the above symptoms doesnt mean they are under the influence.. they may have a mental disorder, be having a reaction to a prescribed med, it could be a sign of an illness like infection, cancer, etc.. Also, someone may be on one of these drugs and not exhibit any of the common s/s associated with the drug.
if you end up working somewhere that you commonly encounter these kinds of patients like the ER, Psych unit or a detox facility, you will get better at figuring it out. but as i said before, there will be a tox screen done on them if it is pertinent to their care.
if you were referring to prescribed meds, well there are thousands of them.. and they should bring that information with them to the hospital.