Tolerance, Dependence and Withdrawal

Tolerance, dependence, addiction and withdrawal are not interchangeable terms. A person can be physically dependent without being addicted. Withdrawal can also occur with antidepressants, which NICE discusses separately from dependence forming medicines. Safe reduction may take weeks, months or longer.

Four related but different ideas Tolerance means that repeated exposure produces a smaller response to the same dose. It may develop to one effect of a medicine more than another. Tolerance does not automatically mean that the dose should increase. Reduced benefit can also reflect a changing condition, an interaction, missed doses, poor technique or a treatment that no longer suits the person. Physical dependence means that the body has adapted to the medicine's regular presence. Reducing or stopping it can then produce withdrawal symptoms. Physical dependence can develop during appropriate prescribed use and does not by itself mean misuse or addiction. Addiction involves a strong desire to take a medicine and difficulty controlling its use, often despite harm or use outside the agreed purpose. Addiction and physical dependence can occur together, but they are not the same. Withdrawal symptoms appear after a medicine is reduced, stopped or sometimes missed. Withdrawal does not prove addiction, and not everyone develops it. Different medicines carry different risks NICE withdrawal guidance covers opioids, benzodiazepines, Z drugs, gabapentinoids and antidepressants. These groups differ in how dependence, tolerance and withdrawal may appear. Benzodiazepines include medicines such as diazepam and lorazepam. Z drugs include medicines such as zopiclone and zolpidem. Gabapentinoids include gabapentin and pregabalin. Opioids, benzodiazepines, Z drugs and gabapentinoids can cause physical dependence and addiction. Antidepressants can cause withdrawal symptoms, but NICE discusses them separately from dependence forming medicines. Other medicines may require gradual reduction for different reasons. Longer or high dose corticosteroid treatment can reduce the body's own cortisol production. This is not the same mechanism as addiction. A medicine should therefore not be labelled addictive simply because stopping it suddenly can cause symptoms. Tolerance can be selective The body does not always become equally tolerant to every effect of a medicine. One benefit may become weaker while important unwanted effects remain. A request for a higher dose can be a clue to tolerance, but it is not proof of addiction. The clinician reviews benefit, harm, the treatment aim and how the medicine has actually been used. Do not increase the dose or add another medicine to restore the previous effect without advice. This can increase the risk of overdose and interactions. Withdrawal varies between medicines and people Withdrawal symptoms can affect physical and mental health. Possible symptoms include anxiety, poor sleep, sweating, nausea, dizziness, tremor, unusual sensations, pain or palpitations. The pattern depends on the medicine, dose, duration, formulation and individual person. Symptoms may begin quickly, appear later or change during the reduction. Some people have mild symptoms, while others experience severe or prolonged withdrawal. The process can last several months or longer for some people. Abrupt benzodiazepine withdrawal can cause severe confusion, loss of contact with reality or seizures. Other medicines have different serious risks, so emergency advice must remain medicine specific. Withdrawal, rebound and relapse can resemble each other Rebound means that the original symptom returns temporarily more strongly after a medicine is reduced or stopped. Relapse means that the underlying condition has returned. Withdrawal symptoms can resemble both. Symptoms beginning soon after a dose reduction, new symptoms or a pattern that feels distinctly different may support withdrawal. These clues are not definitive. A clinician may also need to consider a new illness, an adverse effect or progression of the original condition. Tapering is an individual process Tapering means reducing a dose in planned stages. Its purpose is to lower withdrawal risk while balancing any harm from continuing the medicine. There is no universal tapering percentage or timetable. The plan depends on the exact medicine, current dose, duration of use, previous withdrawal symptoms, other medicines and available support. For several medicine groups, reductions often become smaller as the dose becomes lower. A published schedule is a starting framework rather than a rigid calendar. The person and healthcare professional should agree the pace. If symptoms become intolerable, the next reduction may be delayed, made smaller or reviewed after returning to the previous tolerated dose. Withdrawal symptoms can still occur during a careful taper. This does not mean that the person has failed or that withdrawal is impossible. Abrupt stopping may occasionally be necessary because of a serious adverse effect. That decision requires urgent medicine specific assessment and closer follow up. Addiction needs support, not blame Possible signs include craving, difficulty controlling use, taking more than agreed, using the medicine for another purpose or continuing despite harm. No single sign confirms addiction by itself. People may feel ashamed or fear losing treatment. A non judgemental discussion helps clarify what is happening and allows safer support. Treatment may involve medication review, psychological support, specialist addiction services or treatment of the original condition. Physical dependence should not be treated as a moral failing. When urgent help is needed Contact NHS 111 for severe or rapidly worsening symptoms after abruptly stopping or reducing a medicine, especially when the correct action is unclear. Call 999 for a seizure, severe confusion or loss of contact with reality, collapse, unresponsiveness or severe breathing difficulty. Call 999 or go to A&E when there is an immediate risk of self harm. Do not abruptly stop or reduce a medicine known to cause withdrawal unless urgent medicine specific advice tells you to do so. This lesson explains general principles. It cannot provide a personal tapering schedule or diagnose dependence, addiction, withdrawal or relapse.

Tolerance, physical dependence, addiction and withdrawal describe different processes. Safe decisions depend on the exact medicine and person, and tapering should be collaborative, flexible and guided by symptoms rather than a fixed timetable.