

Drug addiction rarely begins with a complete loss of control. It often starts with something that appears to work — a way to manage stress, pain, anxiety, difficult feelings or the pressure of everyday life. Over time, what began as occasional use or a way of coping can become something the body or mind increasingly relies on.
By the time someone starts looking for information like this, they usually already sense that something has changed — either in themselves or in someone they care about. Understanding what drug addiction is, how it develops and what to look for can help make sense of that.
Drug addiction looks different depending on the substance and the person. Some signs are visible to others; many stay hidden for a long time. Common patterns include:
Someone does not need to recognise every sign for their drug use to matter. A repeating pattern, failed attempts to stop, or consequences that keep building are all reasons to look more closely. Some people know their use has become a problem but find it hard to name; others are surprised when someone close raises it. Both are common.
Drug addiction is a pattern of drug use that becomes compulsive and increasingly difficult to control, even when it is causing harm.
It is not simply a matter of willpower or moral character. Repeated drug use can change how someone experiences reward, stress, motivation and relief. The drug begins to feel central to coping or functioning, and life may gradually become organised around obtaining it, using it and recovering from it. Addiction can involve illegal drugs, prescription medicines or more than one substance.
Different drugs produce different patterns of dependence, withdrawal and harm. These guides look more closely at the signs and risks associated with individual substances.
Dependence can also develop around medication originally prescribed for pain, anxiety or sleep — including opioid painkillers, sedatives and sleeping tablets. Because the recognition questions and withdrawal risks are different, this is covered separately on our prescription drug addiction page.
Polysubstance use means taking more than one drug, or combining drugs with alcohol (alcohol and cocaine being a popular choice). The substances may be taken together, alternated, or used to manage each other’s effects — alcohol to soften a stimulant comedown, stimulants to feel less intoxicated, sedatives to sleep after cocaine. Where several substances are involved, the full pattern needs to be understood together, because withdrawal risks, mental-health effects and overdose risk can differ from those of any one drug alone.
Most people who develop a drug addiction did not intend to. Use that begins socially, recreationally or during a difficult period can gradually shift in frequency, purpose and importance. Tolerance may develop, meaning more of the drug is needed for the same effect. Someone may begin using more often, using alone, or planning their time around the drug.
Several factors can make addiction more likely to develop:
These are not reasons for blame. They help explain why drug use may have become difficult to interrupt, and what may need to be understood alongside it.
Dependence develops when the body or mind adapts to repeated drug use and begins to rely on it. Dependence and addiction are not identical, although they commonly occur together.
Physical dependence means that reducing or stopping a drug produces physical withdrawal symptoms. Their nature and severity depend on the substance, how much is used, how long it has been used, and whether other substances are involved.
Psychological dependence means feeling compelled to use a drug to manage emotions, stress, sleep, social situations or the sense that normal functioning is not possible without it. It can be powerful even where withdrawal is not medically dangerous — cravings, low mood, sleep disruption and familiar routines can all make returning to use hard to resist.
Our guide to drug withdrawal explains how symptoms differ between substances, and when medical advice is particularly important — because some forms of withdrawal should not be attempted without support.
The health risks depend on the substance, how it is used, the amount involved and the person’s wider health.
Physical risks may include damage to the heart, liver, kidneys, lungs or nervous system. Opioids and sedatives carry overdose risk, particularly when combined with alcohol or other depressants. Stimulants such as cocaine place strain on the cardiovascular system. Ketamine can cause serious and sometimes irreversible damage to the bladder and urinary tract. Injecting any drug carries additional risks, including infection and blood-borne viruses. The individual substance guides above cover these risks, and how they develop, in more detail.
Psychological risks may include anxiety, depression, paranoia, impaired concentration and psychosis — caused by drug use, worsened by it, or so intertwined it is hard to say which came first. Drug addiction can also affect relationships, employment, finances, housing and legal circumstances, and these often build gradually in a way that makes asking for help feel harder.
Many people affected by drug addiction are also living with anxiety, depression, trauma, ADHD or other mental-health difficulties. Sometimes the mental-health difficulty came first and drugs became a way of managing it; sometimes repeated use contributed to worsening mood, anxiety or instability. Often the two have become difficult to separate.
This overlap is sometimes called dual diagnosis, or a co-occurring condition. Our guide to what dual diagnosis means explains why addiction and mental health often need to be understood together.
Drug addiction affects more than the person using. Families may carry worry, exhaustion, broken trust, financial pressure and uncertainty about what to do or say. People close to the person may have spent months or years checking what is happening, covering responsibilities, responding to crises or trying to persuade them to stop.
Our support for families and loved ones provides information for people trying to understand what is happening and how they can respond.

The most appropriate support depends on the drugs involved, whether dependence or withdrawal has developed, the effect on physical and mental health, and what has happened during previous attempts to stop. Some people begin with their GP or a local community drug service. Others need more structure, medical oversight, or time away from an environment closely connected to their drug use.
Where structured residential care may be appropriate, read about drug rehab at Abbington House. You do not need to have it worked out before you speak to someone — that is often what the first conversation is for.
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