"Addictive substances" refers to drugs or substances that can cause a strong dependence or addiction. It means these substances can make people want to keep using them even if they know it can harm their health or wellbeing. Full definition
The use of addictive substances in sports is briefly addressed, and one player discusses his past addiction with drugs and alcohol. (parentpreviews.com)
Any illness or disease contracted due to intake of alcohol or other addictive substances will not be covered. (policybazaar.com)
So, as with any other highly addictive substance, if you want to end the addiction and start living without it, you'll need to give it up completely! (fitgirlsdiary.com)