If a Cyantian on Earth got severely injured, thay can accept human blood. It just has to be the same type as their own and their types are very similar to human types. Plantigrade Cyantians would have fewer problems with it, but for digitigrades not quite as well. It'd suffice, but their own blood types would work better for them. In an emergency, they can all use human blood. *Native Cyantians cannot use human blood, nor can they accept other Cyantians' blood.
The effects common Terran medical drugs, such as asprin, have on Cyantians would depend on the drugs. Not all of the drugs made on Earth exist on Cyantia, and neither do the materials they are made from. Common household drugs like aspirin could have worse effects on a Cyantian than a human because of their concentration. Cyantians are relatively healthy and don't take a lot of medicines for their problems unless they have really serious ones, and they aren't in nearly the same strength. For most drugs, just imagine that the recommended dosage would be equivalent to the overdosing amount in a Cyantian. They'll get sicker quicker on too much sugar and alcohol as well. *And yes, they are healthier because they don't take so much medicine for every single ache and pain.*