Bunions are an enlargement of the big toe or hallux joint of the foot and are frequently related to what is called hallux valgus that is a deviation of the big toe towards the outside. They may or may not be painful, though the possibility of them to be painful is great. For that reason prevention and therapy is typically warranted. They certainly tend to be progressive to get worse with time. Really the only way to get rid of them is with surgery, but that is not always a good alternative in the beginning. One of many ways in which they is often dealt with is with what is called bunion correctors, however they are frequently accompanied by the question, do they work? These are splints or braces put on during the night to try and correct the deviation of big toe to improve its appearance.
A great deal is determined by what is meant by “working”. There's a lot of opinion as to bunion correctors both working and not working with almost no scientific evidence. There exists one published scientific study which did show that the angle of the big toe can be improved by a few degrees after one months use, but this was not a study of any longer than that one month. Thus, yes, it does look like that bunion correctors can work in the short term at improving the angle of the hallux valgus or bunion several degrees.
Apart from that one piece of research just about all we can depend upon is expert opinion. Most of that opinion is in keeping with that scientific study. Nonetheless, it also looks like even if the use of the bunion corrector does not improve the angle of the great toe or hallux or only improves it a tiny amount, it is feasible that the corrector can go a long way to preventing the condition from getting worse. That's important as bunions are progressive. The splint may also be very useful at stretching the ligaments surrounding the joint which may be useful with pain inside the bunion.