Bunions are an enlargement of the big toe joint of the foot and are commonly associated with what is called hallux valgus which is a deviation of the big toe towards the outside. They may or may not be painful, but the potential for them to be painful is great. For that reason prevention and treatment is typically warranted. They do tend to be progressive and get worse over time. The only real way to get rid of them is with surgery, but that is not always a good option initially. One way in which they could be treated is with what is known as bunion correctors, but they are frequently accompanied by the question, do they work? These are splints or braces worn at night to try and correct the angle of big toe to improve its appearance.
A lot will depend on what is meant by “working”. There is a lot of opinion as to them both working and not working with very little scientific evidence. There is one published scientific study that 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. So, yes, it does appear that bunion correctors can work in the short term at improving the angle of the hallux valgus or bunion a few degrees.
Apart from that study all we can rely on is expert opinion. Most of that opinion is consistent with that research study. However, it also appears that even if the use of the bunion corrector does not improve the angle of the big toe or only improves it a small amount, it is entirely possible that the corrector can go a long way to preventing the problem from getting worse. That is important as bunions are progressive. The splint may also be very helpful and stretching the ligaments around the joint and that may be helpful with pain inside the joint.