Need reasonable physical indicator of drug use

[Lord Ben]

Is it a magic seed or just a simple chemical reaction type drug?

Go with something like "When staring into the eyes by (magic?) candle light you can see shimmers of pale dim light within the black of the eye, some suspect this is a sign mournful souls have taken up residence in the head." or something a bit less real world drug type reactions.

 

[Ayaka Di'rutia]

His irises turn black and his pupils turn white, and when he cries, his tears are a sickly yellow-green. The skin around his eyes darkens. Maybe more obvious than you were looking for, but it's definitely not an ordinary reaction.

 

[MattR]

As you already know signs given here are only immediate effect of drug use, and not long term exposure.
From what I've seen on patients, drugs that are ingested usually leave stains on teeth, gums, and tongue. They also leave cracked, pale lips. Usually regular use of substances leaves mark on the area of administration. If you want it to be eyes, then it should be administered as ophthalmic drops; or, of course, use the idea of rings around the pupils

When people discuss Halos & Eyes they're usually referring to seeing rings around a light source which would not be noticeable to another person. A rare condition does exist where a grayish/white or less common purple ring can be seen around a person's iris by an onlooker. From my understanding these can be caused by accumulated fats and can signal elevated cholesterol or they can be caused by mineral deposits.

If your fantasy stimulant were mineral based then perhaps the ring being caused by a growing mineral deposit would be plausible and interesting. The more a person uses, the wider the ring around the iris... Serious addicts would be easy to spot. A beginning or infrequent user would attract less attention & may be able to camouflage their addiction.

do you mean Wilson's Disease?

 

[Snowpoint]

The most interesting fake drug I've seen in two movies --- Eye Drop Drugs. It looks so simple to use and easy to conceal, it's hard to believe it isn't real or mainstream by now.

 

[MattR]

The most interesting fake drug I've seen in two movies --- Eye Drop Drugs. It looks so simple to use and easy to conceal, it's hard to believe it isn't real or mainstream by now.

It's because eyes are very sensitive, and the drug would have to be in the same Hp level of the body (hard to achieve if we want it to have any effect). It does seem cool, but medically not realistic