30 Signs of Drug Use: How to Tell If Your Loved One Has an Addiction

Has your loved one been acting “off” lately? Do you have reason to suspect that drug use may be the cause of their behavior?

The following list of signs and symptoms of drug use can be used as a guideline when trying to determine whether or not you should ask them about their substance use. If you do choose to discuss your concerns with your loved one, be sure to approach the topic from a place of genuine care and concern. Spitting accusations will cause the individual to recoil, but compassion can have a significant impact.

Also keep in mind that everyone has bad days that can’t automatically be equated with signs of drug use. Maybe they’re moody because they’re going through a particularly rough patch at work. Maybe they’re exhausted and cranky because they’re adjusting to a new diet or sleep schedule. Maybe they’re flighty and exhilarated because they’ve recently fallen in love and are expressing their joy. In short, don’t ignore your gut instincts, but approach the topic of substance use with caution.

Contact us if you need any help with this process.


  1. Sudden/Uncharacteristic Changes in Behavior. Humans are creatures of habit, so people tend to maintain the same basic demeanor and personality traits throughout their lifetime. Therefore, behavioral changes that arise suddenly and without notable cause may be an indication of some sort of substance use.
  2. Withdrawal from Family and/or Friends. Individuals struggling with addiction tend to move from social drug use to use in isolation in order to keep up their habit. They prioritize the drug over once important elements of life, like spending time with loved ones. Withdrawal could also be an indication of a co-occurring mood disorder, which can exacerbate the addiction if not treated properly.
  3. Mood Swings. Drugs physically change the brain and therefore cause emotional and mental side effects. Of course, mood swings affect everyone from time to time, so frequency and intensity of the emotional shifts are important to consider. Mood swings are another potential indication of a co-occurring mood disorder that should be addressed along with the substance use as applicable.
  4. Loss of Interest in Favorite Activities. Drugs take priority over everything for individuals in active addiction. This fixation can result in apparent apathy regarding prior interests, activities, hobbies, etc. This should not be confused with the natural loss of interest that everyone experiences from time to time as we “grow out of” certain hobbies and move on to new ones. Substance users typically replace old hobbies with drug use, as opposed to a new, healthy interest, so it may appear as though they have no hobbies at all.
  5. Disheveled Appearance. Personal grooming often falls by the wayside as users devote extra time to obtaining and using drugs. The individual may spend extended periods of time in locations where drugs are being sold or used, and may not return home to attend to hygiene since they have “everything they need” already. This also ties into the apathy that users feel for most everything other than getting high.
  6. Altered Sleep Schedule. Drugs alter the body’s natural ability to feel sleepiness, fall asleep and remain asleep. Users may find that it is easier to get high or obtain substances under the cover of night when they’re less likely to be caught, so they may inadvertently reverse their sleep schedule. Some drugs cause the user to feel “wired”, resulting in sleeplessness and restlessness for extended periods of time. One common misconception is that alcohol and other drugs help users to get to sleep at night, when actually the body has to work extra hard to process the toxic substance. The brain cannot refresh and focus on sleep when the body is working to metabolize the drugs, so the quality of sleep deteriorates.
  7. Abnormal Appearance of the Eyes. Eye functioning and appearance is a relatively easy way to determine whether or not something is physiologically altered in an individual. Drugs affect the Central Nervous System, which in turn affects various functions of the eye. For example, depressants reduce the frequency of blinking, causing dryness and a glassy appearance. They can cause enlarged pupils and wide, unresponsive stares. Stimulants can cause nervousness and agitation, which may result in darting, rapid eye movements. Squinty, red eyes are commonly associated with marijuana use, as the active compound THC causes blood vessel dilation, which increases blood flow to the eyes (and other locations.)
  8. Changes in Appetite and/or Weight. Some drugs suppress appetite. Some drugs increase appetite. Either way, noticeably unhealthy changes in eating habits are abnormal and problematic. In active addiction, substance use takes precedence over nutrition and scheduled eating patterns so weight fluctuations are a fairly common occurrence. The drugs may also cause lethargy or a lack of motivation to exercise, which can contribute to weight gain and/or muscle loss.
    Rapid changes in weight
  9. Mental Confusion. Drugs have an effect on the higher-processing functions of the brain so users often act with characteristic bewilderment. The confusion may present as jumbled speech, repetitive question asking, an inability to understand even simple tasks, etc. Neurological disorders or pathologies extending to the brain can also have this effect, so be sure to rule out any outstanding physical health issues before deciding that drugs are definitely the cause.
  10. Impulsivity and/or Loss of Control. Many drugs alter the decision-making and reasoning parts of the brain, so users may find it difficult to resist certain impulses. Addiction itself is a disease of impulse control, so these tendencies tend to manifest in many instances of life. Some individuals are non-pathologically impulsive, so be sure to take into account the severity and frequency of the occurrences. If the loss of control seems non-characteristic, substance use may be to blame.
  11. Changes in Speech. Different drugs have a number of different effects on speech. Common changes include increase talkativeness, decreased talkativeness, jumbled speech, slurred speech, nonsense speech, etc. Changes should be compared to normal patterns of speech for the individual in question. For instance, if the person is naturally introverted, then an increase in talkativeness may be more notable and significant than an increase for extroverts.
  12. Abnormal Reaction Times and/or Excitability Levels. Substance use can significantly alter reaction times and extents. What once seemed exciting to the individual may invoke a neutral response while on drugs. What once seemed like no big deal to the individual may cause an extreme reaction while on drugs. The user may respond too quickly or too slowly to be appropriate for the situation. This principle applies to speech, muscle movement, emotional response, etc.
  13. Delusions of Grandeur. Certain drugs can make the user feel invincible. The neurological effects of the substance, tied with the physiological numbness and other euphoric symptoms often cause the individual to take risks without understanding the actual consequences. Some individuals are naturally narcissistic and/or overly confident to the point where grandiose statements would not be totally uncharacteristic. For individuals with less extreme personalities, though, these delusions should be carefully considered.
  14. Excessive Nervousness, Anxiety, Suspiciousness, and/or Paranoia. Illegal substance use can understandably cause paranoia, since there are legal implications to being caught. Even legal substances can cause this anxiety, for example if an individual’s parents forbid drug use then discover that their child is drinking and smoking behind their backs. Drugs can also cause physiological changes that bring about nervousness, though. Stimulants especially are known for activating the sympathetic nervousness, which is responsible for “fight or flight” responses. Arousal of this branch of the nervous system causes an increase in heart rate and other symptoms of anxiety to prepare the body for the threat that the brain perceives.
  15. Excessive Aggression, Agitation, and/or Violence. Drugs are disinhibiting, so the user is more likely to participate in violent, aggressive, or even criminal activities. This is especially true with alcohol, though stimulants have also been linked to an increase in violence. Stimulants cause hyper-emotionality, hyper-alertness, paranoia, etc., which in turn make the user more likely to act on impulse. Aggression can also be learned from environments of drug distribution, in which tensions are high and disputes are common.
  16. Unusual Sweating or Chills. Certain substances affect temperature regulation in the body, causing overheating and sweating, or chills and shivering. Drugs can also alter the structure and function of blood vessels throughout the body. Dilated blood vessels allow more blood to flow through them. This increased blood flow results in increased heat transfer to the skin, which the body releases through sweating. Constricted blood vessels restrict the amount of blood allowed to flow through them. This decreased blood flow results in decreased heat transfer to the skin, so shivering is induced to create more heat.
  17. Abnormal Motor Control: Shaking, Stumbling, Slowed Movement, Etc. Drugs can affect many parts of the body implicated in motor control, coordination, and balance, and can therefore cause a whole range of motor symptoms. For example, users may be seen shaking, stumbling, moving too slowly or quickly, clenching their teeth, clenching their fists, constantly contracting their muscles, etc. Stumbling while walking is a notorious sign, and the reason behind the “walk in a straight line” test that police sometimes administer to drunk drivers. Some users will move slowly in either a deliberate attempt to seem normal, or because they cannot process the surrounding stimuli quickly enough to move any faster. Other users will move quickly due to hyperactivity, paranoia, etc. Physical tenseness can also result from emotional tenseness, as well as poor muscle control. Shaking is a common sign of withdrawal, though it may also occur while the substance is still present in the body.
  18. Reported/Observed Hallucinations or Other Altered Perceptions. Substance users trying to hide their addictions are unlikely to report hallucinations to a concerned loved one. They may, however, unintentionally report them while attempting normal conversation. For example, they may reference a stimulus that isn’t present, like a strange sound they can hear or an object in the room that does not exist. You can also sometimes pick up on hallucinations or altered perceptions through observations alone, for example if the user is excessively fixated on a seemingly normal item or if they are frantically looking around for something that doesn’t seem to be real.
    Hallucinations may be signs of drug use
  19. Changes in Sexual Desire. Hyper-sexuality is another example of disinhibiting behavior; drug users are more likely to engage their primal, sexual instincts. Pleasure-seeking behavior defines addiction so being unable to control hormonal, sexual urges can be a notable indicator of extensive drug use. Hypo-sexuality can also indicate drug use, though, by inhibiting endocrine and neural functioning in the body. Any sexual changes from their norm can serve as grounds for concern, really.
  20. Getting high can paradoxically result in extreme lows. Drugs alter the reward circuitry in the brain so that normally pleasurable activities no longer satisfy the user in the same way. The individual gets stuck in a cycle of using drugs in an attempt to reverse the anhedonia, but only exacerbates the addiction. After a while even the highs become more depressing from dreading the low. Depression is also a common psychiatric disorder without substance use, so keep that in mind, especially if the potential-user has a family history of the illness.
  21. Skin Discoloration. Red, flushed skin is a common sign of alcohol use in particular, but drugs can also cause other forms of skin discoloration, some permanent. They can cause accumulations of certain substances to build up under the skin, causing altered pigmentation on the surface. They can cause allergic reactions/inflammatory responses that may result in discoloration. They may also cause damage to various parts of the body, including blood vessels, which may end up scarring their physical appearance.
  22. Frequent Nausea and/or Vomiting. Drugs are mostly foreign, toxic substances that the body needs to metabolize and detox out in some way or another. Vomiting is especially common during overdoses, during which the body can no longer process the concentration of the drug and has to physically eject it to prevent serious damage or death. These symptoms are very generalized and can apply to a wide variety of illnesses, so look at context clues to determine whether or not they are potentially stemming from drug use. For example, does the vomiting usually occur after a long night out with friends? Is the nausea accompanied by other symptoms on this list?
  23. Impaired Thinking. Faulty reasoning, rash decision making, delayed reaction times, inability to form a coherent sentence…these are all warning signs for impaired thinking that could potentially be caused by drug use. Regularly impaired thinking could be a result of neurological damage that needs immediate medical attention; intermittently impaired thinking, though, is most likely a sign of substance use.
  24. Signs of Euphoria. Euphoria goes beyond the normal happy, contentedness of a non-using individual. It usually arrives unannounced and unprovoked and is evidenced by unusually long-lasting grins, excessive and uncontrollable laughter, random giggling, smiling eyes, etc. Euphoria is usually only present when the user still has the drug in their system and several instances of unreasonable euphoria should be observed before assuming that drug use is the cause.
  25. Self-Destructive Behavior. Drug use in itself is a self-destructive behavior, but it may also bring on other forms. Lack of inhibition may result in risky, destructive behaviors, such as unsafe sex, drunk driving, fighting, etc. In an altered state of consciousness, users may also reason that self-destructive behavior is necessary. For example users of LSD (acid) have been known to feel trapped in their skin and attempt to tear it off as a result. Consider urging your loved one to consult a psychiatrist as soon as possible for evaluation of another potential mental illness.
  26. Administration Scars. Scars on the arms, hands, and in other administrative locations often define injection sites. The marks vary in appearance based on the frequency and precision of the injection; they may appear as red, irritated scabs, raised scarring over a vein, dark red/purplish vein discoloration, bruising, bumps, “track marks,” etc. Scarring can theoretically come from giving blood, accidents, etc. but if scars are consistently showing up then it may be time to have a discussion with your loved one.
  27. Frequent Fainting/Unconsciousness. Passing out is very commonly associated with drug overdose. If you find that your loved one has fallen unconscious, you should keep their airway open and seek medical attention as soon as possible. Losing consciousness has detrimental effects on the brain and deserves urgent attention.
  28. Extreme Lethargy and Laziness. Chemically induced lethargy may be difficult to identify if your loved one lives a non-active lifestyle on a normal basis. Something is likely amiss, though, if they can be found in bed more often than not, if they miss regular activities and obligations due to laziness, and/or if they lack the motivation and energy to pursue former interests. Lethargy is a common symptom of many medical ailments, so physical illness should be ruled out by a professional.
    A messy room
  29. Unusual Odor. Some drugs possess a characteristic smell, for example marijuana clings to users with a skunk-like fragrance that is detectable for a long time after use. You might also be able to smell various burnt materials from smoking, or an excess of Febreeze (or another odor-neutralizer) used to cover up the odor.
  30. Obsessive or Defensive Denial of Use. Some substance users attempt to cover up their habit by denying it defensively and sometimes even without provocation. They may make it obvious that they are using drugs by the excessive amount that they protest, or by the way do so: avoiding eye contact, speaking quickly, wringing their hands while talking, etc. If your loved one won’t admit to having a problem even when you are 100% positive that they do, then it may be time to consider an intervention or seeking another form of external assistance.

What should I do if I recognize these signs in someone I know or love?

Please feel free to contact us, and we can help walk you through what to do next if someone you know or love is suffering from a substance use problem. We are here to help.


Sources Cited:


Leave a Comment

Your email address will not be published. Required fields are marked *

Call us at (708) 613-4750

or message us below and one of our caring counselors will reach out to you.

Scroll to Top