Substances | 5 min read

How to Tell if Someone Is High on Drugs

Medically Reviewed

Medically Reviewed By

Dr. Po-Chang Hsu

Dr. Po-Chang Hsu

On March 4, 2024

Written By

Amanda Stevens

Amanda Stevens, B.S.

On March 4, 2024

How To Tell If Someone Is High

What you will learn

  • Identification of being under the influence of a substance will vary as different drugs will produce different “highs.” Check this guide for reference.
  • Many substances can lead to dependence and addiction, more so for several risk factors, including childhood aggression, little parental guidance, difficulty managing peer pressure, past drug use, prevalence of drugs in school, and poverty.
  • Experiencing a “high” has a significant potential for adverse effects.
  • If you believe you or someone you love is under the influence of a harmful substance, seek medical attention immediately if it is safe to do so.
Reading Time: 5 minutes

People are creatures of habit. The more time you spend with someone, the better you know their predictable habits, routines, quirks, turns of phrases, etc.

You can probably predict their cadence of footsteps as they walk down a flight of stairs, the specific brand of cereal they pick in the morning, and the words with which they choose to greet you. If they start acting out of character, you might wonder if they are high.

If your family member or friend is exhibiting unusual behavior, it’s important to consider various factors, including but not limited to the possibility of substance use. It’s possible they need medical attention or an addiction treatment program. This guide provides information on recognizing potential signs of substance use, but it’s important to approach such situations with understanding and seek professional advice.

Symptoms of Drug Exposure

There are many different kinds of drugs, but not all drugs have psychoactive qualities. Once absorbed, psychoactive drugs alter your mental processes, such as mood, cognition, and emotions.[1]

Depending on which kind of drug the person you know might have taken, they will exhibit different symptoms. There are, broadly speaking, seven different types of psychoactive drugs[2]:

How to Tell if Someone is High on Stimulants

How to tell if someone is high on stimulants.

Stimulants are substances that stimulate the speed at which messages get sent between the body and brain inside the central nervous system. Stimulants can include drugs like caffeine, nicotine, amphetamines, and cocaine.[3]

Small doses of stimulants might make users appear:

  • Alert
  • Energetic
  • Confident

Excessive stimulant dosing might cause symptoms like[4]:

  • Anxiety
  • Panic attacks
  • Seizures
  • Headaches
  • Cramping
  • Overt aggression
  • Paranoia

How to Tell if Someone is High on Depressants

Depressants are substances that depress the speed at which messages get sent between the body and brain inside the central nervous system. Depressants can include drugs like alcohol, benzodiazepines, GHB (Gamma-hydroxybutyrate), and kava.[5]

Small doses of depressants might make users appear:

  • More relaxed
  • Gregarious
  • Happy
  • Sad
  • Angry

Excessive depressant dosing might cause symptoms like[6]:

  • Slurred speech
  • Glassy eyes
  • Confusion
  • Unconsciousness
  • Vomiting
  • Seizures
  • Trouble breathing
  • Slow heart rate
  • Clammy skin
  • Low body temperature
  • Dulled gag reflex (prevents choking on vomit)

How to Tell if Someone is High on Opioids

Opioids are substances that attach to opioid receptors in your brain and blunt the subjective experience of pain.

While they mimic the experience of natural hormones like dopamine, they are much stronger and produce much more powerful (and addictive) results. Opioids can include drugs like morphine, codeine, heroin, fentanyl, and oxycodone.[7]

Small, therapeutic doses of opioids might make users appear:

  • Drowsy
  • Numb
  • Content

Excessive opioid dosing might cause symptoms like[8]:

  • Euphoria
  • Excessive fatigue
  • Constipation
  • Pinpoint pupils
  • Blue or gray skin
  • Unconsciousness

How to Tell if Someone is High on Psychedelics

Psychedelics are substances that alter a user’s mood, thoughts, and perceptions of reality. While they aren’t generally addictive, your body can build a tolerance to them.

While overdosing on psychedelics alone is possible, it’s extremely unlikely.[9] Psychedelics can include drugs like LSD, magic mushrooms, and mescaline (peyote cactus).

Any level of psychedelic dosing might make users appear[10]:

  • Euphoric
  • Paranoid
  • Fearful
  • Anxious
  • Confused
  • Uncoordinated
  • Disorganized

How to Tell if Someone is High on Cannabinoids

Cannabinoids are any substance that binds to the cannabinoid receptors of the body and brain. These chemicals are found in the Cannabis Sativa plant. Cannabinoids can include drugs like synthetic cannabis, medicinal cannabis, and cannabidiol.[11]

The main psychoactive compound in marijuana is THC. Small, therapeutic doses of THC in the form of regular cannabis are usually more associated with pain relief and relaxation, but psychedelic effects like hallucinations have been reported following excessive THC dosing[12].

Small, therapeutic doses of cannabinoids might make users appear:

  • Relaxed
  • Happy
  • Allergy-prone via bloodshot eyes
  • Unsanitary via musty earthy smell
  • Unmotivated
  • Paranoid

Excessive doses of cannabinoids might cause symptoms like[13]:

  • Daily cough and phlegm
  • Cyclical, severe nausea
  • Paranoia
  • Hallucinations
  • Worsening of schizophrenia

How to Tell if Someone is High on Dissociatives

Dissociatives are any substance that disrupts communication between neurotransmitter systems, including, but not limited to, bodily sensory perception.[14] While they often mirror the effects of depressants, they have a unique set of effects.

Users of these substances often report the subjective experience of “depersonalization,” where they feel disconnected from their own bodies. Dissociatives can include drugs like ketamine and PCP (Phencyclidine).

Small, therapeutic doses of dissociatives might make users appear:

  • Euphoric
  • Numb
  • Nauseous
  • Unconscious

Excessive doses of dissociatives might cause symptoms like[15]:

  • Hallucinogen persisting perception disorder (HPPD) (hours, days, weeks, months, or even years)
  • Engaging in dangerous behavior
  • Depressed breathing and heart rate
  • Urinary tract infection-like symptoms (ketamine-induced uropathy)

How to Tell if Someone is High on Empathogens

Empathogens are substances that signal the brain to release and/or block the reuptake of three neurotransmitters: Serotonin, norepinephrine, and dopamine. The largest neurotransmitters released by quantity due to MDMA are serotonin and norepinephrine.[16]

Serotonin regulates your mood, while norepinephrine helps you stay alert and focused.

Empathogen users often feel a sense of greater “connectedness” to the people around them. This newfound trust can be dangerous, especially if combined with dissociatives because it deprives the user of correctly identifying threat-related facial emotional signals while simultaneously feeling disconnected from their own body.[17]

This leaves them vulnerable to rape and sexual violence. Empathogens can include drugs like MDMA, mephedrone, and ethylone.

Small doses of empathogens might make users:

  • Cheery
  • Friendly
  • Empathetic
  • Self-confident
  • More touchy-feeling than usual
  • Playful

Large doses of empathogens might cause symptoms like[18]:

  • Depression
  • Confusion
  • Anxiety
  • Paranoia
  • Memory loss
  • Terrible mood (due to depleted serotonin levels)
  • High body temperature
  • Nausea
  • Chest pain
  • High Blood Pressure

Statistics on Drug Use

Half of all people aged 12 and older in the US have used illicit drugs at least once.[19] And since data collection began in the year 2000, over 700,000 Americans have died from overdosing on drugs.[20] That’s a little more than the entire population of Colorado Springs.

In 2021, over 106,000 people in the US died from overdosing on drugs–the highest ever recorded.[21] Alcohol and marijuana were the two most commonly used substances.

Drug use during childhood development makes the user more susceptible to long-term substance use addiction. 90% of people with a substance use disorder started smoking, drinking, or using drugs before they turned 18.[22]

Risk Factors of Drug Addiction

Risk factors are “association,” NOT “causation.”

“Causation” implies cause and effect. This directly produces that. “Association” implies an indirect but statistically significant relationship. This has some effect on that.

Risk factors for drug use are different choices, environments, or traumas that can put an individual at greater risk for drug addiction. Some risk factors for drug use are:[23]

  • Childhood aggression
  • Little parental supervision or guidance
  • Difficulty saying “no” to peer pressure
  • Past drug use
  • Prevalence of drugs in school
  • Poverty (both in the home and in the community)

The Highs Aren’t Worth The Harm

If you are suffering from the effects of drugs, seek treatment immediately. There are treatment centers near you that will offer compassionate and professional care as they craft an individual recovery plan using a variety of addiction therapies just for you. Sobriety is not wishful thinking. You can regain control of your life today.

Frequently Asked Questions

What Does it Mean When Someone is High?

When we call someone “high,” it means they are experiencing the initial (generally desired) effects of an administered drug. Usually, these effects are ones that prompted the drug use in the first place.

Depending on which type of drug was taken, the “high” will be different.

A caffeine high will present differently than a cocaine high, even though they are both stimulants. An alcohol “buzz” (which is a colloquial term for an alcohol high) will present differently than a benzo high, even though they are both depressants.

Some highs are more dangerous than others. While consuming too much caffeine can leave you with shaky hands and a racing heart, it is not nearly as dangerous as a heroin high, which can depress your heart rate until it triggers cardiac arrest.

Being “high” is not always taken seriously by the public at large and can be construed as “socially playful,” a “youthful indiscretion,” or even “harmless.” This is far from the truth.

When you are high, you will not have optimum control over your body to escape dangerous situations. Even if you do escape situational danger, the long-term consequences could compound and produce undesirable results.

What Things Do People Do When They Are High?

Many people take drugs to experience things they believe they cannot experience while sober.

Some people take MDMA to remove their sexual inhibitions before an encounter. Little do they realize they also leave themselves vulnerable to date rape and sexually-transmitted diseases (from not using protection like condoms).

Some people drink alcohol to make themselves more socially gregarious. The initial flood of dopamine will help their mood perk up, but after the rush comes the depressant effects, which last for much longer.

Some people take LSD to experience a distorted reality. While they may indeed experience it, they also leave themselves vulnerable to persistent hallucinations that remain long after the high recedes.

Regardless of why it is taken, drugs always take more than they give. After the high subsides, you will be forced to endure whatever other side effects remain.

What are the Effects of Marijuana?

Marijuana (aka weed) has a range of possible effects, including euphoria, relaxation, heightened sensory and altered time perception, laughter, and the “munchies” (increased appetite)[24].

If you are suspicious someone is high on marijuana, several physical symptoms could be present:

  • Bloodshot eyes (looks like an allergic reaction)
  • Unsteady (muscle coordination is lacking)
  • Munchies (increased appetite for sweet, salty, or fatty foods)
  • Delayed reaction times
  • A pungent odor (could be described as earthy, musty, or skunk-like)

Marijuana is only just beginning to be seriously studied, and much of its long-term effects are unknown. It’s possible that marijuana has an adverse effect on the cognition of developing brains.[25] THC can cause permanent changes in fetal development in expecting mothers. It can also be passed through breast milk.

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Here at Ascendant New York, we understand the importance of having access to accurate medical information you can trust, especially when you or a loved one is suffering from addiction. Find out more on our policy.

Amanda Stevens


Amanda Stevens, B.S.

Amanda is a prolific medical content writer specializing in eating disorders and addiction treatment. She graduated Magna Cum Laude from Purdue University with a B.S. in Social Work. Read more

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[1] World Health Organization. (n.d.). Drugs. World Health Organization.

[2][5] Drug Wheel. Drug facts – alcohol and drug foundation. (n.d.).

[3][4] Stimulants. Stimulants – Alcohol and Drug Foundation. (n.d.).

[6] U.S. Department of Health and Human Services. (n.d.). Understanding the dangers of alcohol overdose. National Institute on Alcohol Abuse and Alcoholism.

[7] Opioids. Opioids – Alcohol and Drug Foundation. (n.d.).

[8] Opioid use disorder – statpearls – NCBI bookshelf. (n.d.).

[9] (PDF) LSD overdoses: Three case reports – researchgate. (n.d.-b).

[10] Psychedelics. Psychedelics – Alcohol and Drug Foundation. (n.d.).

[11] Cannabinoids. Cannabinoids – Alcohol and Drug Foundation. (n.d.).

[12] Barrett, F. S., Schlienz, N. J., Lembeck, N., Waqas, M., & Vandrey, R. (2018, March 1). “hallucinations” following acute cannabis dosing: A case report and comparison to other hallucinogenic drugs. Cannabis and cannabinoid research.

[13][25] U.S. Department of Health and Human Services. (2023, July 28). Cannabis (marijuana) Drugfacts. National Institutes of Health.

[14] Hallucinogens and Dissociative Drugs – National Institute on Drug Abuse … (n.d.-a).

[15] U.S. Department of Health and Human Services. (2023a, June 1). Psychedelic and dissociative drugs. National Institutes of Health.

[16] MDMA’s effects on the brain | (n.d.). drugfreeCT.

[17] Bedi, G., Hyman, D., & de Wit, H. (2010, December 15). Is ecstasy an “empathogen”? effects of ±3,4-methylenedioxymethamphetamine on prosocial feelings and identification of emotional states in others. Biological psychiatry.

[18] Empathogens – Alcohol and Drug Foundation. (n.d.).

[19][20] Substance abuse and addiction statistics [2023]. NCDAS. (2023, January 1).

[21]U.S. Department of Health and Human Services. (2023, September 25). Drug overdose death rates. National Institutes of Health.

[22] Fast facts about addiction. Partnership to End Addiction. (2023, June 26).

[23] U.S. Department of Health and Human Services. (2020, July 13). Drug misuse and addiction. National Institutes of Health.

[24] NIDA. 2019, December 24. Cannabis (Marijuana) DrugFacts. Retrieved from on 2024, June 14