In case of emergancy:

"Pharmacy at the main station"
Mon-Fri from 6 a.m. to 10 p.m.
Sat 8 a.m. - 10 p.m. and Sun 8 a.m. - 6 p.m.
http://www.apotheke-im-hauptbahnhof-koeln.de/index.html
 
 
The nearest hospital:
St. Marien Hospital
Kunibert monastery 11-13
50668 Cologne
Tel. 0221-1629-0
http://www.st-marien-hospital.de/