Would it be safe to go on rollercoasters if I have "tennis elbow"?

Very likely. In this situation, the symptoms of tennis elbow would likely only be worsened if you were repetitively or very strenuously gripping something for long periods of time while on a roller coaster. I doubt you should avoid a roller coaster just because of tennis elbow.

Related Questions

Can you go on rollercoasters if you have "tennis elbow"?

Yes. The only way it would become worse from riding a roller coaster is if you hang on for dear life and strain the muscle or bang the elbow on the car during the ride. Otherwise it is safe. Read more...