Adequate Directions for Use
The "adequate directions for use" requirement is a core US labelling concept with no direct equivalent in other frameworks. It underpins the prescription/OTC device distinction.
The requirement
Under 21 CFR § 801.5, labelling must bear adequate directions for use — directions under which a layperson can safely use the device for the purposes for which it is intended.
"Adequate directions for use" means directions that are:
- Stated in ordinary terms
- Include the quantity of each application
- Include any frequency of application
- Include the duration of application
- Include any relevant precautions, warnings, and contraindications
Prescription device exemption
Devices that are restricted to sale by or on the order of a licensed practitioner (prescription devices) are exempt from the adequate directions for use requirement under 21 CFR § 801.109 — because a layperson is not the intended end user.
Instead, prescription device labelling must include adequate information for practitioners, including:
- Indications for use
- Effects, routes, methods, and frequency of use
- Relevant contraindications, side effects, and precautions
Exemption for OTC devices already in common use
Some OTC devices (those sold directly to consumers without a prescription) are sold with labelling that achieves adequate directions for use through the combination of label and IFU.
Official resources
Example of adequate directions: 'Apply thin layer to affected area twice daily for 7 days. Do not use on broken skin. Stop use if rash occurs.' Inadequate directions might use medical jargon without explanation or omit frequency entirely. The FDA evaluates 'ordinary terms' from the perspective of a typical consumer without medical training.