Skip main navigation

New offer! Get 30% off one whole year of Unlimited learning. Subscribe for just £249.99 £174.99. New subscribers only T&Cs apply

Find out more


Sustained use of a substance commonly leads to other issues, such as tolerance and withdrawal.
Man unaffected after several drinks
© CQUniversity 2021

Sustained use of a substance commonly leads to other issues, such as tolerance and withdrawal. Tolerance and withdrawal are telltale signs that substance use is turning into an addiction.


Tolerance can be defined as a need for increased amounts of the substance to achieve intoxication or the desired effect. It may also present as a markedly diminished effect with continued use of the same amount of the substance, causing the person to increase their use of the substance to feel the same effect.

Example – Alcohol

Emily is 22, she has 3-4 drinks of an evening after work, and frequently binge drinks with friends on a weekend consuming anywhere from 10 – 15 standard drinks between 5 pm and 11 pm. This pattern of behaviour has been going on for 6 months, and Emily has started to notice she isn’t feeling as fun and intoxicated after her usual number of drinks.

Emily thinking about having another drink

This is due to tolerance. Humans develop a tolerance when their brain learns to function under the influence of that amount of alcohol. To feel the same effects Emily needs to drink even more alcohol. This increases her risk of becoming even more dependent on alcohol and the risk of alcohol-related organ damage.

© CQUniversity 2021
This article is from the free online

Understanding Addiction

Created by
FutureLearn - Learning For Life

Reach your personal and professional goals

Unlock access to hundreds of expert online courses and degrees from top universities and educators to gain accredited qualifications and professional CV-building certificates.

Join over 18 million learners to launch, switch or build upon your career, all at your own pace, across a wide range of topic areas.

Start Learning now