In short. The situations in which this treatment should not be given: muscle disease, difficulty swallowing, and the widths that do not respond however often they are treated.
Key points
- Whether there is any condition affecting muscle strength, and whether it is stable.
- Whether swallowing has ever been difficult, and whether food or drink has ever gone the wrong way.
- Whether there is a history of aspiration or of a chest infection after eating.
Most of this site is about deciding whether treatment is worth having. This guide is about the situations in which it should not be given, which is a different judgement and one that belongs first. Some of those situations are medical, some are about the kind of width a patient has, and some are about what she is expecting.
Where the muscle is already weak
A condition that affects muscle strength, or the way nerves and muscles meet, changes the calculation entirely. Where a muscle already works below its normal strength, quietening it further is not a treatment for appearance, and the assessment ends in a different conversation. The history answers this rather than the examination, which is why the first appointment asks about weakness, about double vision and about difficulty with speech or swallowing that comes and goes.
What the assessment asks before anything else
Whether there is any condition affecting muscle strength, and whether it is stable. Whether swallowing has ever been difficult, and whether food or drink has ever gone the wrong way. Whether there is a history of aspiration or of a chest infection after eating. Whether any medicine is being taken that affects muscle activity. An answer to any of those changes the plan, and sometimes ends it.
Where swallowing is affected
The muscles of the jaw and the throat work together in swallowing, and reducing the activity of a muscle in that group is not appropriate where swallowing is already a problem or has been one. The assessment is straightforward: it is asked about, and where an answer raises the question it is looked into before treatment rather than after.
The widths that do not respond
A width that comes from the mandible does not narrow with an injection, however many courses are given. Neither does a width that comes from fat over the jaw. Neither does a difference between the sides that has appeared recently and is progressing, because that is a finding to be explained rather than a muscle to be reduced. And neither does a face whose width is not, on examination, what the patient believes it to be, which deserves a conversation rather than a treatment.
Expectations that rule treatment out
A patient who wants a specific face from a photograph, a patient who wants the corner of the jaw to disappear, and a patient who needs an appearance that does not change are each asking this treatment for something it does not do. None of that is a criticism of the patient. It means the treatment she asks for is not the one that would help her, and saying so is the most useful thing an assessment can do.
Situations in which this is not offered
- A condition affecting muscle strength, or a history of difficulty swallowing.
- A width coming from the bone, from fat, or from a difference that is progressing.
- A request for a result that holds, or for a specific face from a photograph.
Frequently asked questions
Why is swallowing asked about before a masseter injection?
Because the muscles of the jaw and the throat work together in swallowing, and reducing the activity of a muscle in that group is not appropriate where swallowing is already a problem or has been one at some point. It is a short question with a long history behind it, and a patient who answers it honestly saves herself a treatment that should not have been given to her.
How does the assessment tell that my width is the wrong kind?
By feeling the muscle at rest and under clench, comparing the two sides, and allowing for what the bone and the fat over it are contributing. A muscle that softens at rest and stands out on clenching is contributing. A width that stays hard, or that changes with body weight, is coming from something else, and imaging is added where the bone has to be measured rather than felt.
If I am told no, is there anything that would help instead?
Usually there is something, and it is a different treatment rather than nothing. A skeletal width is a matter for an operation on the bone. A width from fat is a matter for reducing fat. A habit that is loading the muscle is worth a dentist's opinion, because a guard protects the teeth and the joint even though it does not reduce the muscle. Saying no to this treatment is not the same as saying no to help.
Risks & Limitations
- The effect is temporary by design. The muscle is quietened rather than damaged, so the width returns over months unless the clenching habit itself has changed.
- A change to the smile and tiredness with hard food are the effects most often noticed at this site, and both usually settle as the effect fades.
- The treatment narrows only the width the muscle is producing. A width coming from the bone or from fat is not changed by it.
- No outcome can be promised, and how much of the width the muscle explains is established only at an assessment.
When to Seek Care
- Difficulty swallowing, or food or drink going the wrong way — seek medical assessment the same day.
- A weakness that spreads beyond the jaw, or any change in breathing — seek emergency care immediately.
- A fullness at the jaw that is warm, red or painful, or that is growing steadily.
- Fever with swelling that spreads beyond the jaw, or a smile change that is worsening rather than settling.
References & Further Reading
- American Society of Plastic Surgeons (ASPS) — procedure and safety guidance
- National Institute for Health and Care Excellence (NICE, UK) — relevant guidance
- Cochrane Library — systematic reviews
- Chinese Medical Association Plastic Surgery Branch — clinical guidance
This page is patient education, not medical advice, and it does not cite individual studies. Discuss your own case with a qualified clinician. To arrange an assessment at Chongqing West District Hospital, see Contact & Consultation.