Effects of Drugs & Alcohol

A drug's effects depend partly on how it reaches the blood, travels through the body and is broken down or removed. These processes differ between substances.

A swallowed substance may be absorbed through the stomach or small intestine. Blood then distributes it. The liver breaks down many drugs, and the kidneys help remove many drugs or their breakdown products. Not every substance follows exactly the same route.

The same amount can affect people differently. Age, body size, food eaten, other drugs and the condition of organs can influence the effect. A dose that seems familiar to one person is not proof that it is safe for someone else.

A drug's half-life describes the time taken for its concentration in blood to fall by half under stated conditions. It does not, by itself, tell us exactly when every effect ends. Health professionals use this information when planning treatment; it is not a guide for experimenting with drugs.

Psychoactive means affecting the brain in ways that can change mood, perception or behaviour. A substance does not have to be illegal to be psychoactive. Alcohol, caffeine and nicotine are familiar examples.

Depressants slow central nervous system activity. Alcohol is one example. Stimulants increase alertness and can raise heart rate; caffeine and nicotine belong to this group. Hallucinogens alter perception and can cause someone to experience things that are not present.

These groups are useful descriptions, not a complete list of every drug type. A drug can have several effects, and some effects overlap between groups. Effects can also change with the amount taken and with other substances used at the same time.

Legal status answers a different question: what a law permits. It does not identify a drug's biological effects or establish that using it is harmless.

Alcohol is a depressant. Someone may feel more talkative after drinking, but alcohol can still impair judgement, coordination and reaction time. How lively someone feels is not a reliable measure of whether their reactions are impaired.

The liver breaks down most alcohol. Long-term heavy drinking can damage liver tissue and cause scarring. Alcohol's effects are not limited to the liver; it can affect other organs and behaviour too.

Some prescribed medicines also have depressant effects. A medicine can have a useful purpose while still carrying risks. Mixing alcohol with certain medicines or other drugs can increase danger. A pharmacist or clinician can explain medicine-specific risks.

Dependence can develop with repeated use. For someone physically dependent on alcohol, suddenly stopping can cause dangerous withdrawal. Medical support matters; this reading does not give instructions for stopping or treating withdrawal.

Nicotine is a psychoactive substance in tobacco. It has stimulant effects and can cause dependence. A person may develop strong urges to use it and experience withdrawal when use stops.

Tobacco smoke is a mixture of substances, not one chemical. It contains chemicals that damage the lungs and chemicals that can cause cancer. Nicotine dependence can keep someone smoking, but nicotine alone is not the explanation for smoking-related lung cancer.

Caffeine is also a stimulant, but sharing a group does not mean two substances have identical effects or risks. A broad category describes some effects; it does not replace information about the particular substance.

Tolerance means that the same dose has less of an effect after repeated use. It does not mean that damage has stopped or that taking a larger amount is safe.

Physical dependence develops when the body adapts to a drug. Withdrawal can follow when the drug is reduced or stopped. Psychological dependence involves strong urges to use a drug or feeling a need to use it to cope. Both can occur together.

Tolerance and dependence are related ideas, but tolerance alone does not establish that someone has an addiction. Addiction involves problems with controlling use despite harmful consequences. A clinician considers more than one symptom when assessing someone.

Support depends on the substance and the person's needs. It may include supervised withdrawal care, medicines, talking treatments or other ongoing support. There is no single treatment that fits every person or drug.

People, places or feelings associated with past use can bring back urges. Returning to use does not mean someone is beyond help. A trusted adult or health professional can help a young person find appropriate support. Someone dependent on alcohol should seek medical advice about stopping because withdrawal can be dangerous.