which he/she has lawfully obtained for his/her personal medical use, or for administration to an animal 

accompanying him/her, may enter or depart the United States with such substance notwithstanding 

sections 1002-1005 of the Act (21 U.S.C. 952-955), provided the following conditions are met:

(a) The controlled substance is in the original container in which it was dispensed to the individual; and

(b) The individual makes a declaration to an appropriate customs officer stating:

(b1) That the controlled substance is possessed for his/her personal use, or for an animal 

accompanying him/her; and

(b2) The trade or chemical name and the symbol designating the schedule of the controlled substance
if it appears on the container label, or, if such name does not appear on the label, the name and 
address of the pharmacy or practitioner who dispensed the substance and the prescription number. 

© In addition to (and not in lieu of) the foregoing requirements of this section,
a United States resident may import into the United States no more than
50 dosage units combined of all such controlled substances in the individual's
possession that were obtained abroad for personal medical use. 

(For purposes of this section, a United States resident is a person whose residence
(i.e., place of general abode—meaning one's principal, actual dwelling place in fact, without regard to intent)
is in the United States.) 

This 50 dosage unit limitation does not apply to controlled substances lawfully obtained in the
United States pursuant to a prescription issued by a DEA registrant.

[69 FR 55347, Sept. 14, 2004, as amended at 81 FR 97019, Dec. 30, 2016]