Bunions are an enlargement of the big toe joint of the foot and are commonly associated with what is called hallux valgus that is a deviation of the big toe or hallux towards the outside. They may or may not be painful, though the prospect of them to be painful is great. For that reason prevention and treatment will be typically indicated. They do tend to be progressive and get worse with time. Really the only way to get rid of them is with surgery, but that is not necessarily a good option in the beginning. One of many ways in which they is often treated is by using what is known as bunion correctors, however they are usually accompanied by the question, do they work? They are splints or braces put on during the night in an attempt to correct the angle of big toe to better its appearance.
A lot will depend on what is meant by “working”. There's a lot of thoughts and opinions as to them both working and not working with very little scientific evidence. There is one published scientific study which did reveal that the angle of the great toe will be improved by a few degrees after one months use, but this was not a study of any more than that one month. Thus, yes, it does appear that bunion correctors can work in the short term at improving the angle of the hallux valgus or bunion several degrees.
Apart from that piece of research all we can depend on is expert opinion. The majority of that opinion on bunion correctors is consistent with that research study. Nonetheless, it also looks like even if the use of the bunion corrector does not help the angle of the great toe or only helps it a smaller amount, it is feasible that the corrector may go quite a distance to preventing the condition from getting even worse. That is significant as bunions are progressive. The splint might also be very useful at mobilizing the ligaments surrounding the joint which might be useful with pain within the bunion.