21 CFR § 801.5 - Medical devices; adequate directions for use.
Adequate directions for use means directions under which the layman can use a device safely and for the purposes for which it is intended. Section 801.4 defines intended use. Directions for use may be inadequate because, among other reasons, of omission, in whole or in part, or incorrect specification of:
(a) Statements of all conditions, purposes, or uses for which such device is intended, including conditions, purposes, or uses for which it is prescribed, recommended, or suggested in its oral, written, printed, or graphic advertising, and conditions, purposes, or uses for which the device is commonly used; except that such statements shall not refer to conditions, uses, or purposes for which the device can be safely used only under the supervision of a practitioner licensed by law and for which it is advertised solely to such practitioner.
(b) Quantity of dose, including usual quantities for each of the uses for which it is intended and usual quantities for persons of different ages and different physical conditions.
(c) Frequency of administration or application.
(d) Duration of administration or application.
(e) Time of administration or application, in relation to time of meals, time of onset of symptoms, or other time factors.
(f) Route or method of administration or application.
(g) Preparation for use, i.e., adjustment of temperature, or other manipulation or process.