Digestive 
Blood
Cardiovascular
Dermatology
Genitourinary,
Hormones
Infections
Oncology and
Musculo-skeletal
Mental health and
Parasites
Respiratory
Senses
Various
The most common routes of administration include injection (e.g. heroin), smoking (e.g. cannabis, snuff), oral (e.g., synthetic drugs, alcohol), sniffing (aspirated) (e.g. speed [amphetamine sulphate], cocaine) and inhalants (e.g., solvents, glues).
Whatever the route of administration, dependence occurs accompanied by a series of physical and psychological symptoms, including:
- Strong desire to consume the substance.
- Difficulties to control use.
- Withdrawal when consumption is stopped or reduced.
- Tolerance.
- Progressively abandoning interests that are not related to the use of the substance.
- Persistence in using the substance despite clearly perceiving its harmful effects.
