It could be her embouchure that is causing the problem. There are at least two typical types of embouchure. One, where you fold your lower lip over your lower teeth, which I don’t care for as it can damage your lip. The second is where you don’t place your lower lip over your teeth rather you push the lower lip right up to the reed without going over your teeth, which I prefer. The second type takes a little getting used to if you began with the over the lip embouchure because you need to build up strength since you are using some different muscles than you do with the first type of embouchure. You can also purchase lip guards for reed players that prefer the over the lip method.

Above all other advise i would suggest she see a saxophone teacher. Once you develope bad habits, it is hard to break them as you get older.

It could be a couple of things. She may be a biter. This can happen when we get tired or when we don't relax enough.

It may be that her reeds are too soft and she is fighting them. It is hard to know without actually checking the student out.

Get a teacher ASAP!