Different people are affected in different ways, so there is no exhaustive checklist that can be consulted. However, some of the common signs of drug or alcohol addiction include:
* Unpredictable behaviour
* Insomnia or oversleeping
* Pupils that are either very large or very small
* Slurred speech
* Lack of motivation
You may also find physical signs such as empty bottles, small plastic bags, scraps of cling film, and drug paraphernalia including bent spoons or syringes.
Please keep in mind that there are many other things which can cause changes in behaviour. Keep a close eye on your loved one if you suspect something is wrong.