- Active ingredient
- The substance in a medicine responsible for its intended effect.
- Addiction
- Difficulty controlling medicine or substance use despite harmful consequences. It is a health problem requiring support; it is not the same thing as physical dependence alone.
- Benzodiazepine
- A class of medicines including diazepam, lorazepam, clonazepam and nitrazepam. Their uses differ, and they can cause sedation, dependence and withdrawal.
- Brand name
- The name a manufacturer uses for its medicine product.
- Contraindication
- A circumstance, such as a particular condition or medicine combination, in which a treatment should not be used. The exact contraindications are listed in the product information.
- Dependence
- Physical adaptation to a medicine, so reducing or stopping it may cause withdrawal symptoms. Dependence can occur during prescribed use and does not automatically mean addiction.
- Dose
- The amount of medicine taken on a particular occasion, according to the instructions for that person. Dose is different from the strength printed on one tablet or capsule.
- Generic medicine
- A medicine described by its active ingredient rather than a particular brand name. Formulation and prescribing instructions still need checking before a product is substituted.
- Half-life
- The time it takes for the amount of a medicine in the body to fall by about half. It is not a countdown to when driving or taking another medicine becomes safe.
- Hypnotic
- A type of medicine used to help with sleep.
- Interaction
- When a medicine, substance or product changes the effect of another. Interactions can alter effectiveness or adverse effects; a pharmacist can check the exact combination.
- Opioid
- A class of medicines used for pain, including codeine, dihydrocodeine and tramadol. These medicines can cause constipation, sedation, dependence and dangerous effects on breathing.
- Patient information leaflet
- The document supplied with a medicine explaining its use, warnings and possible side effects.
- Sedation
- Reduced alertness or increased sleepiness caused by a medicine or other substance. It can affect coordination, judgement and the ability to drive safely.
- Side effect
- An unwanted effect that may happen when using a medicine.
- Strength
- The amount of active ingredient in a specified unit, such as one tablet or capsule. For a combination product, two numbers may describe two separate ingredients.
- Tolerance
- When the body becomes used to a medicine and its effect can become weaker.
- Withdrawal
- Symptoms that can occur after a medicine is reduced or stopped when the body has adapted to it. Some medicines need an individually planned reduction rather than abrupt stopping.
- Z-drug
- A term used for certain sleeping medicines, including zopiclone and zolpidem.
Sources & further reading
General information to help you prepare questions for a healthcare professional. Source pages checked on 1 November 2026.
