I did a little research for you, hope this helps

Who Can Donate Blood?
In general you ARE ELIGIBLE to donate blood if:
# You are 17 years old or older. There is no upper age limit.
# You weigh at least 110 pounds
# You are in good health. If taking medication, you may be able to donate depending on the reason for and the type of medication. .
Persons taking most medications are able to donate blood.
Medications that do not prevent you from donating:
* High Blood Pressure Medications
* Insulin (by mouth or injection)
* Allergy Medications
* Asthma Medications
* Anti-depressants
* Aspirin
* Cholesterol Lowering Medications
* Seizure Medications
* Diet Pills