ATC (Anatomical Therapeutic Chemical) Codes

ATC Codes Explained

We publish ATC codes for each medicine on the Find a medicine webpage. You can use the ATC Code to search for individual medicines or groups of medicines using the Advanced Search tab.

The ATC code is the World Health Organisation (WHO) classification system for medicines. The WHO assigns ATC codes to active substances (ingredients) contained in medicines based on the use of the medicine (therapeutic indication).

Using the ATC code, active substances are classified in groups at five levels. The grouping is based on three factors:

• the organ or body system on which the active substance acts (Level 1)
• its therapeutic, pharmacological and chemical properties (Level 2-4)
• the active substance (Level 5)

In some cases, an ATC code is partially assigned with a reduced number of levels.

Level Classification ATC Code

Here is an example of an ATC code for a medicine containing the active substance omeprazole for the treatment of acid reflux and ulcers in the gut:

All medicines containing omeprazole as a single active substance are given the ATC code A02BC01; Medicines containing omeprazole and additional active substances are given a separate but related ATC code.