Roxanne
All medications have side effects and can be dangerous if not used properly. However, some side effects you should immediately call your doctor. These include:
Increased heart rate
Slow heart rate
Cold hands or feet
Mood changes or depression
If you are experiencing any of these, you should contact your doctor and discuss this with them.
There is some detailed information about Clonidine here. This will provide you with additional information on side effects and things to watch for.
I hope this helps
Eileen