Self-medication is use of a drug with therapeutic intent but without professional advice or prescription.
There are legal constraints on self-medication, however, and there is a psychiatric hypothesis which links drug abuse and addiction to self-medication.
Some drugs, including aspirin and paracetamol, are licensed for sale for self-medication, and licensed manufacturers (pharmaceutical companies) combine them with other substances to create a wide rage of branded products sold over the counter.
Also, legal use may be made of drugs such as alcohol and tobacco which are not covered by drug control laws.
Possession of prescription-only drugs for self-medication may be legal, but such drugs are not legally supplied for this purpose, and both supply and possession for self-medication of drugs which are within the scope of the United Nations Single Convention on Narcotic Drugs and Convention on Psychotropic Substances are generally illegal.