Drugs don’t just affect your physical body and health, they can affect your mental health, your finances, your relationships, your social life and your criminal record.
Physical effects can vary
The way a drug affects you depends on:
- the drug itself
- what type of drug it is
- how you took it
- how much you took
- how strong or pure it is
- how often you take it
- your own body
- your gender
- physical size
- mood
- personality
- expectations
- how recently you ate
- your general health
- have you become tolerant?
- what other drugs you took with it – for example, alcohol.
Each drug causes different physical reactions, depending on the type of drug. Some will make you feel more awake, alert and energetic. Others will give you a calm, relaxed feeling. Some alter your perceptions and can cause hallucinations. Others may make you feel numb.
Long-term use and larger doses have negative effects that can seriously harm your health, even cause death, including disease risks from sharing needles, and permanent damage to the brain and other organs.
Visit the Alcohol and Drug Foundation website to learn about individual drugs and their effects.
Other effects
Mental health
Studies show that drug use increases your risk of mental health issues such as anxiety, depression and psychosis. People with mental health issues also have a higher rate of drug use problems.
Financial issues
Some drugs can be very expensive – the street price of illicit drugs depends on availability and demand. If you have become dependent on a drug, you could end up in financial trouble.
Illicit drug use causes a significant burden to the Australian economy. For example, the estimated total social costs for methamphetamine alone are around $5 billion annually – through crime, loss of productivity and increased health care costs.
Relationships
Because drugs can change your behaviour, they can affect your relationships with family and friends. There is an increased risk of injury and/or assault to both yourself and other people.
Legal issues
Many drugs are illegal and you can be fined, or sent to prison, for having them. If convicted of a drug offence, you could end up with a criminal record – this can make it harder to get a job, apply for a loan, or travel overseas.
Learn more about Australia’s drug laws.
Drugs in sport
Sports people and professional athletes who use illegal substances risk damaging not only their physical health, but also their reputation and the integrity of their sport.
The Australian Sports Anti-Doping Authority (ASADA) protects the health of athletes and implements anti-doping programs, including drug testing.
Drugs and driving
Alcohol and other drugs can seriously affect your driving skills. You are more likely to have an accident, injuring yourself and/or others. The crash could be fatal.
The different types of drugs affect your driving ability in the following ways:
- stimulants – driving too fast or erratically, being aggressive behind the wheel, reduced vision, you can feel overconfident
- depressants – driving too slowly, falling asleep at the wheel, veering out of your lane, your reactions are slower
- hallucinogens – distorted vision, hard to correctly judge distances, seeing things that aren’t there.
Mixing drugs, including alcohol, only increases your risk of having a crash.
It's illegal to have any trace of illicit drugs in your system when driving.
Learn more about the consequences of driving under the influence of alcohol and other drugs on the Alcohol and Drug Foundation website.
How your body processes drugs
Your body processes drugs in 4 stages:
- Absorption
When you use a drug it is absorbed into your bloodstream. How quickly this happens depends on how you took the drug. - Distribution
Once a drug is in your bloodstream it circulates through your body, being distributed to different organs and the brain. The drug affects chemicals and receptors within the brain, causing different effects depending on the type of drug. - Metabolism
Your body then metabolises the drug or breaks it down into simpler molecules (known as metabolites) which can be more easily eliminated. Sometimes these metabolites can also affect your body. - Excretion
Metabolised drugs go through your digestive system and exit your body, usually in urine or faeces.
How long your body takes to eliminate a drug varies. It depends on many factors, including the drug itself (how much you took, how strong, etc) and you as an individual (your metabolism, age, health, environment, etc).
Read more about how drugs are detected.
Come down
As drugs are processed and eliminated from your body, the effects wear off – you experience a ‘come down’. The after-effects vary depending on what drugs were taken and can be mental and/or physical. They commonly include:
- depression
- insomnia or sleepiness
- extreme tiredness.
You may also experience:
- headaches
- nausea
- loss of appetite.
Read more about managing the effects of a come down on the ReachOut website.
Drug tests
Testing to see if there are drugs in your body may be done:
- to detect illegal drug use
- when you’re driving
- in some workplaces
- in sports.
There are different types of drug tests – they look for traces of drugs in your:
- saliva
- blood
- urine
- breath
- sweat
- hair.
A negative test result only happens if:
- you have not taken any drugs
- your body has broken down the drug and eliminated it from your body.
Drugs stay in your system for varying lengths of time. Visit the Drug Aware website for more information on how long drugs can be detected.
What is a bad reaction or ‘trip’?
A person using drugs can sometimes have a bad reaction – also called a ‘bad trip’. This is often linked to hallucinogenic drugs.
The intensity of the high experienced during a bad trip can be overwhelming and frightening and the user can become unstable, even violent. They risk harming themselves and/or others around them.
Contact the National Alcohol and Other Drug Hotline if you need help or advice. Of course, if it’s an emergency, phone 000 and ask for an ambulance.
Drug overdose
Taking too much of a drug, including prescription drugs, can result in an overdose. Each person will react differently, but death can occur in some cases. Even if the person recovers there can be permanent damage to their body.
If you or someone you know is at risk of overdosing, this is a medical emergency. Phone 000 immediately and ask for an ambulance.
Polydrug use
Mixing drugs or taking multiple drugs together is known as polydrug use. Examples of polydrug use include:
- smoking cannabis after drinking alcohol
- mixing alcohol with energy drinks containing caffeine
- combining alcohol with prescription drugs.
This can be extremely dangerous as the effects can be unpredictable — they will depend on which drugs have been taken together. For example, combining drugs with similar effects (stimulants, depressants or hallucinogens) increases the impact on your body.
Read more about mixing drugs on the Drug Aware website.
Drug addiction and dependence
Anyone can become addicted to alcohol or drugs.
Not everyone who tries drugs will become regular users, and not all regular users become dependent. There are many factors involved and it varies between people and drugs.
Using a drug regularly can lead to tolerance – your body becomes used to the drug and needs increasingly larger doses to achieve the same effect.
Regular use can also lead to dependence – where you need the drug to feel good and function normally. Dependence can be physical, psychological or both.
Being addicted means continuing to use a drug even though you’re aware of the harmful consequences. Addiction can be:
- physical – your body craves the drugs, for example, alcohol, nicotine
- mental – your mind needs the drug in order to forget your problems or relax
- social – you feel you need the drug in order to fit in or enjoy social events.
If you stop taking a drug or try to reduce the amount you’re taking you may experience withdrawal symptoms. These can be physically and mentally unpleasant and may include:
- tiredness
- hunger
- depression
- being irritable
- aggression
- anxiety
- paranoia
- cravings for the drug.
Learn more about withdrawal on the Alcohol and Drug Foundation website.
Find out how you can reduce or quit drugs.
Medically reviewed by Alyssa Peckham, PharmD, BCPP — Written by Jamie Eske — Updated on June 19, 2022
- Mental effects
- What is SUD?
- Getting help
- Treatment
- FAQs
- Summary
Substance use disorder can lead to short- and long-term negative health effects. These effects can be physical and mental and can range from moderate to severe.
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Generally, drug misuse or SUD refers to the use of psychoactive drugs, which are substances that affect the brain. The effects on the body depend on the type of substance a person uses and their health history.
Examples of common psychoactive drugs include:
This article discusses the physical and mental effects of substance use disorder.
Psychoactive drugs are chemical compounds that affect the mind and body.
Taking different drugs may cause:
- changes in coordination
- blood pressure and heart rate changes
- feelings of being more awake or sleepy
- improved sociability
- pain relief
- changes in the appearance of a person’s body
When chronic substance use occurs over a long period, these short-term physical effects may cause long-term changes to a person’s brain and body.
The specific physical effects of substance use may vary among individuals and depend on the substance, dosage, delivery method, and length of use.
Substance use can sometimes lead to serious health consequences, including overdose and death.
Short-term physical effects
Using any drug can cause short-term physical effects. The following are examples of common drugs, their short-term physical effects, and potential health risks due to SUD.
- alcohol
- methamphetamines
- increased wakefulness and physical activity
- decreased appetite
- increased breathing
- increased or irregular heart rate
- increased blood pressure
- increased temperature
- cocaine
- narrowed blood vessels
- enlarged pupils
- increased body temperature, heart rate, and blood pressure
- headache
- abdominal pain and nausea
- erratic and violent behavior
- heart attack
- stroke
- seizure
- coma
- benzodiazepines
- slurred speech
- dizziness
- problems with movement
- slowed breathing
- lowered blood pressure
- heroin and other opioids
- dry mouth
- itching
- nausea
- vomiting
- slowed breathing and heart rate
- tobacco and nicotine
- increased blood pressure
- increased breathing
- increased heart rate
- tobacco or nicotine:
- greatly increased risk of cancer — lung cancer due to smoking or oral cancer due to chewing
- chronic bronchitis
- emphysema
- heart disease
- leukemia
- cataracts
- pneumonia
Long-term physical effects
Using substances for an extended time may have long-term health consequences. These lasting effects depend on multiple factors, including the substance, the amount, and how long a person has used it.
Examples of commonly used drugs and potential long-term physical effects of SUD include:
- alcohol:
- stroke
- liver disease and inflammation (alcoholic liver disease)
- pancreatitis
- digestive problems
- cancer of breast, mouth, throat, esophagus, voice box, liver, colon, and rectum
- weakened immune system
- alcohol use disorder or alcohol dependence
- methamphetamines:
- severe dental problems
- weight loss
- intense itching leading to skin sores
- risk of HIV, hepatitis, and other diseases from shared needles
- cocaine and heroin — when a person snorts them, these drugs may cause:
- loss of sense of smell
- nosebleeds
- nasal damage and trouble swallowing
- other effects include:
- infection and death of bowel tissue from decreased blood flow
- inadequate nutrition and weight loss
- collapsed veins
- abscesses
- infection of the lining and valves of the heart
- constipation and stomach cramps
- liver or kidney disease
- pneumonia
- fatal overdose
- tobacco or nicotine:
- greatly increased risk of cancer — lung cancer due to smoking or oral cancer due to chewing
- chronic bronchitis
- emphysema
- heart disease
- leukemia
- cataracts
- pneumonia
Long-term SUD may affect a person’s memory, behavior, learning, consciousness, and concentration.
Substances, such as alcohol, cannabis, stimulants, and opioids, are psychoactive drugs that may change an individual’s brain function and structure after chronic use. This can result in cognitive and behavioral changes and deficits that may remain even after someone stops using.
The exact mental or cognitive effects of SUD may vary depending on the type of drug and the duration of use.
SUD may also exacerbate symptoms of other mental disorders, and early drug use is a strong risk factor for the later development of substance use disorders. It may also be a risk factor for developing other mental illnesses.
For example, frequent cannabis use in adolescents can increase the risk of psychosis in adulthood in individuals who carry a particular gene variant.
Short-term mental effects
Examples of common drugs and their short-term mental effects include:
- alcohol:
- feelings of euphoria
- reduced anxiety
- easing of social interactions
- irritability and anxiety upon withdrawal
- cannabis:
- enhanced sensory perception
- feelings of euphoria and relaxation
- anxiety
- irritability upon withdrawal
- benzodiazepines:
- drowsiness
- concentration issues
- dizziness
- reduced anxiety
- problems with memory
- heroin:
- feelings of euphoria
- restlessness upon withdrawal
- prescription opioids:
- pain relief
- drowsiness
- feelings of euphoria
- methamphetamine:
- increased wakefulness
- anxiety upon withdrawal
Long-term mental effects
Examples of common drugs and mental effects associated with long-term SUD include:
- alcohol:
- depression
- anxiety
- learning and memory problems
- social problems
- prescription opioids:
- increased risk of overdose
- methamphetamines:
- anxiety
- confusion
- insomnia
- mood problems
- violent behavior
- paranoia
- hallucinations
- delusions
- heroin:
- tobacco and nicotine:
- in teens, they can affect the development of brain circuits that control attention and learning
- irritability, attention and sleep problems, and depression upon withdrawal
- cannabis:
- mental health problems
- irritability, trouble sleeping, anxiety upon withdrawal
To get a diagnosis of SUD, a person has to qualify for 11 criteria that the DSM-5 outlines.
These include:
- using more of a substance than a person intends or using it for longer than they mean to
- trying to cut down or stop using the substance but being unable to
- experiencing intense cravings or urges to use the substance
- needing more of the substance to get the desired effects (tolerance)
- developing withdrawal symptoms when not using the substance
- spending more time getting and using drugs and recovering from substance misuse
- continuing to use even when it causes relationship problems
- giving up important or desirable social and recreational activities due to substance use
- using substances in potentially harmful settings that put a person in danger
- continuing to use despite the substance causing problems to physical and mental health
SUD prevalence
Government data shows that SUD tends to be more common among Black people than Hispanics, Asians, and people who are white. SUD is more common in males among people who are white, Black or African Americans, American Indians or Alaska Natives, and those who identify as two or more races.
However, it is difficult to determine the accuracy of data on racial disparities. In the United States, historically, the “war on drugs” has meant that Black Americans are 6–10 times more likely to be incarcerated for drug offenses even though they are not necessarily more likely to use illegal drugs. This imbalance may impact prevalence data.
In addition, SUD from illegal opioids is a large public health problem in the U.S. that can lead to overdose and death. In some cases, SUD can result from prescription opioids, but the bulk of the crisis stems from illegal or “street” drugs.
More than 760,000 people have died since 1999 from opioid overdoses. In 2018, two out of three overdoses had links to opioid use.
Finding the right treatment program may feel overwhelming. Here are a few things a person can consider when seeking treatment for SUD.
- Consider whether inpatient or outpatient services would be most suitable.
- Find local treatment centers using the Substance Abuse and Mental Health Services Administration’s treatment finder tool.
- Know that state-run treatment centers and programs may be free of charge.
- Look for programs that use evidence-based treatment strategies.
SUD is a complex but treatable disease that affects a person’s cognitive function and behavior. No single treatment is right for everyone.
However, effective treatment for SUD should address all of a person’s mental and physical health needs.
Treatment aims to help individuals develop a healthier relationship with drugs, helping them live productive lives in relationships with their family, work, and society.
Treatment may involve some of the following components:
- Medications: Can help minimize withdrawal symptoms and prevent the return to unsafe use.
- Behavioral counseling: Helps individuals modify their attitudes and behaviors related to substance use, increase healthy life skills, develop problem-solving skills, and stick to treatment plans.
- Group therapy: Gives people the chance to acknowledge, share, and work through the psychological aspects of recovery with a group of peers under professional guidance.
- Additional support: May include vocational training and other resources that address problems associated with SUD, such as mental health conditions, unemployment, and medical conditions.
Here are some common questions and answers regarding SUDs.
How do I know if I or someone I know is misusing drugs?
Healthcare professionals use 11 criteria to determine if an individual has SUD. Some of them include:
- using more of a substance than a person intends
- using it for longer than they mean to
- trying to cut down or stop using the substance but being unable to
- experiencing intense cravings or urges to use the substance
- needing more of the substance to get the desired effects
- developing withdrawal symptoms when not using the substance
What are the risk factors for drug misuse?
Certain factors may increase an individual’s risk for SUD. These risk factors include:
- family history of substance use
- difficulties with parental monitoring
- parents substance use
- family rejection of sexual orientation or gender identity
- association with substance-using peers
- lack of school connectedness
- academic achievement difficulties
- childhood sexual abuse
- mental health issues
SUD can affect several aspects of a person’s physical and psychological health.
Certain substances may lead to drowsiness and slow breathing, while others may cause insomnia, paranoia, or hallucinations. Chronic substance use has links to cardiovascular, kidney, and liver disease.
In addition to physical and mental effects, substance use can adversely affect a person’s relationships, home and work life, and mental health.
Care providers should tailor treatment to a person’s needs. Community-based organizations and state-funded treatment programs usually involve a combination of behavioral therapy, group therapy, and medication.
Last medically reviewed on June 19, 2022
- Mental Health
- Alcohol / Addiction / Illegal Drugs
- Psychology / Psychiatry
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