I occasionally use 50-lb dumbbells for one-hand overhead presses. It takes some mindfulness of form, but otherwise is perfectly safe for me. I like it for when I don't have a lot of time, since I can only do a few reps with each arm.

Part of lifting weights is raw strength, another is proper form. If I can't perform a lift 'the right way', I take off weight until I can. It took a fair bit of practice to