Healy was handed a three-week suspension by tournament organisers which has now been reduced to two.
An appeal committee statement read: "The player had argued, among other things, that by extending the three week suspension over four weekends (to take account of the first 'break weekend' in the 6 Nations Championship) was not permissible under the relevant regulations.
"The independent Six Nations disciplinary appeal committee... upheld the appeal."
Healy's suspension will end at midnight on March 3.
The forward, who missed Ireland's 12-8 defeat by Scotland at Murrayfield on Sunday, stamped on Cole's ankle during a maul in the first half of England's 12-6 victory on February 10.
Ireland are fourth in the standings with one win from three games.
- Sports & Recreation