In short. A muscle-relaxing injectable into the corrugator and procerus: what it changes, how long it lasts, the maintenance pattern, and the limits of relaxing a working muscle.
Key points
- It reaches the fold made by muscle contraction, which is why a crease that vanishes at rest responds most completely.
- It does not reach the groove that decades of folding have left in the skin, which softens rather than disappears.
- And the muscles being quieted hold the inner brow down, so brow position changes as well.
The rung that reaches the mechanism is a relaxing injection: a botulinum toxin of the A type, given into the corrugator supercilii and the procerus so that their pull on the skin is reduced. It addresses why the crease exists rather than what is left of it.
What the category does
The toxin reduces the signal the muscle receives from the nerve ending that supplies it, so the muscle contracts less. The skin it was gathering is no longer folded, and the crease flattens while the effect lasts. It is a temporary reduction in movement rather than damage to the muscle.
It wears off, so the treatment is repeated
The nerve endings recover and the muscle gradually returns to its previous activity, usually over months rather than weeks. Because the effect wears off, the treatment is repeated rather than completed, and each repeat is a fresh decision rather than a standing order, best made after looking at how much movement has returned and how the brow is sitting. Shortening the interval to hold the effect at its peak keeps the balance of the muscles altered for longer stretches and gives the brow more opportunity to drift.
What relaxing the muscle does and does not reach
It reaches the fold made by muscle contraction, which is why a crease that vanishes at rest responds most completely. It does not reach the groove that decades of folding have left in the skin, which softens rather than disappears. And the muscles being quieted hold the inner brow down, so brow position changes as well.
The limits of relaxing a muscle that keeps working
The muscle is not removed and it does not stop working. It returns to folding the skin when the effect wears off, and the etch in the skin continues to accumulate for reasons that include sun exposure and time. This is why the honest description is relief rather than resolution, and why a result is judged against the resting face recorded before treatment rather than against a memory.
What is looked at before it is given
The resting brow position, the height of the medial brow, the position of the lid edge and the amount of movement available are recorded first. The pattern of the creases decides which muscles are treated and in what proportion, and the brow position decides whether the change that follows is one the person wants.
Reasons to pause and seek advice
- A drooping eyelid, double vision, or difficulty swallowing, speaking or breathing after treatment needs emergency care.
- Weakness spreading beyond the face, or a rash with breathlessness, needs urgent assessment.
- A plan offered without anyone recording your brow position and lid height beforehand.
What happens to the brow when these muscles are quiet is covered in the brow position trade-off. What happens when the effect wears off is described in what happens when you stop, and the part of the line it does not reach is set out in resurfacing the etched glabellar line.
Frequently asked questions
How long does the effect usually last?
Months rather than weeks, commonly in the region of three to four, and shorter or longer in individual people. It is judged by when the movement returns rather than by a date in a diary, because the same person can differ from one treatment to the next. Any interval quoted to you is an estimate for planning, and your own plan may differ.
Does the muscle weaken permanently with repeated treatment?
The reduction in movement is temporary each time and the muscle itself is not damaged; the nerve endings recover and the muscle returns to its previous activity. What repeated treatment does is keep the skin from being folded for long stretches, which is a change in the crease rather than in the muscle. Nothing about it is designed to be irreversible.
Why does the treatment change the brow as well as the line?
Because the muscles being quieted are depressors: they hold the inner brow down. With their pull reduced, the frontalis meets less opposition and the medial brow often rises. That change is sometimes wanted and sometimes not, and it is the reason the brow position is measured before treatment rather than looked at afterwards.
Risks & Limitations
- Relaxing the corrugator and the procerus also lifts the medial brow, and in a brow that already sits high that lift can become the complaint rather than the result.
- A drooping eyelid, double vision, or difficulty swallowing, speaking or breathing after an injection needs emergency care rather than a wait-and-see approach.
- Resurfacing carries a risk of pigment change and, rarely, of scarring, and its result is judged weeks after the last session rather than on the following morning.
- No rung removes a crease that is established in the skin. A line that is visible at rest usually softens, and any statement that promises more should be treated with suspicion.
When to Seek Care
- Difficulty breathing, chest pain, or difficulty swallowing or speaking after an injection needs emergency care immediately.
- A drooping eyelid, double vision, or an eye that will not close fully after treatment.
- Weakness or numbness on one side of the face, or a brow that has dropped on one side.
- A crease that has appeared or deepened over weeks rather than years, or any change in vision on one side.
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.