What is botulinum toxin?
Botulinum toxin, or BTX, is a prescription injectable. The medical name is the accurate one, and several formulations exist. You may also see it called anti-wrinkle injections. The doctor selects a formulation for each zone. Potency units are specific to each formulation and cannot be converted between brands, so bring the record of any product you have had before.
BTX blocks the release of acetylcholine where a nerve meets a muscle. The treated muscle contracts less, and that is the aim. That is all it does. It acts on movement and adds nothing to the tissue. A line that shows only when you frown is the kind it targets. A line that is there when your face is still is a different problem.
Good planning is mostly about what to leave alone. Each muscle does a job, and neighbouring muscles matter. A consultation therefore looks at how your face moves, as well as the lines you want to change.
How the assessment works
How Dr Sin Yong sets the dose
Dr Sin Yong sets the dose at consultation from your own muscles, after watching them work, and gives the injections himself. Placement matters as much as amount, because each muscle sits beside others that should keep working.
The examination is live: at rest, on a full brow raise, in a frown, and with the eyes closed and opened again. Photographs of a still face show little in the upper face. The jaw is checked on clenching and neck bands on straining.
Before any forehead plan, he checks the brow against the bony rim of the eye socket, and the upper lids for skin that would rest on the lashes once the forehead stops helping. A forehead that is holding heavy lids open gets a lighter dose, or the plan turns to the lid.
The frown area is usually treated at the same visit as the forehead, so the brows are not pulled down, and bunny lines are considered together with the frown.
One brow often sits higher, or lines run deeper on one side, so each side is dosed for itself rather than copied. The formulation is chosen for each zone, and he asks for the record of any product used elsewhere first, because units cannot be converted between brands.
Dosing starts conservatively. At review he balances early unevenness with a small dose, and decides when, or whether, to repeat.
He does not treat a neuromuscular disorder such as myasthenia gravis, and treatment waits through pregnancy and breastfeeding. A goal the medicine cannot reach, such as erasing lines etched at rest, adding volume or lifting loose skin, is said plainly. No treatment is a normal outcome of a consultation.
“The dose comes from watching the muscle move, not from a chart.”
Which areas is botulinum toxin used for?
| Area | What is targeted | What should keep working | What careful planning tries to avoid |
|---|---|---|---|
| Forehead lines | Frontalis, the only muscle that raises the brows | Enough lift to keep the eyes open and expressive | A heavy or lowered brow |
| Frown lines | Corrugator and procerus between the brows | The brows and the forehead above | A drooping eyelid from spread to the lid muscle |
| Crow's feet | Outer orbicularis oculi at the eye corner | The squint and the smile | A changed smile or a lower lid that sits away from the eye |
| Bunny lines | Nasalis on each side of the upper nose | The lip elevators, so the smile is unchanged | A dropped upper lip |
| Masseter | The bulk of the muscle at the jaw angle | Chewing, with less force | A bulge on clenching, or a change in the smile |
| Neck bands | Platysma cords that stand out on straining | Swallowing and neck movement | Neck weakness or difficulty swallowing |
| Underarm sweating | The nerve signal to sweat glands, not a muscle | Arm and shoulder movement | Treating sweating that is generalised or new in adulthood before its cause is checked |
Why does the forehead need extra care?
The frontalis is the only muscle that lifts the brows. If it is relaxed more than your eyelids can afford, the brow can feel heavy or sit lower. This is why brow position and eyelid reserve are examined first, and why the forehead is not simply treated to stillness. Frown lines bring a separate concern, because the medicine must stay away from the muscle that lifts the eyelid. Around the eye, placement that is too low can change the smile or the position of the lower lid. Near the nose, spread to the lip elevators can drop the upper lip. Each of these is temporary, but none can be reversed on demand. Small changes in placement matter, so conservative doses and accurate placement are part of the plan.
Other areas that may be discussed
Other uses are raised at assessment. These include the DAO muscle that pulls down the corners of the mouth, lip lines, and the trapezius for shoulder bulk. Calf slimming is another request, and any change is gradual. In the jaw, the masseter may lose bulk over several weeks. Contour change from BTX works by reducing muscle bulk, so it only applies where the width or bulk comes from muscle. If it comes from something else, another plan is needed. Underarm sweating is different again. Here the injection acts on the nerve signal to sweat glands in the skin, and a muscle is not involved. Sweating that is generalised, or that is new in adulthood, needs its cause investigated before any treatment. Earlier treatment, sometimes described as preventive BTX, is also discussed. It is not needed by everyone, and it should be weighed like any other prescription treatment.
Botulinum toxin or filler: which do I need?
It depends on what is causing the change you see. Toxin acts on a muscle and suits lines made by movement, such as frown lines, forehead lines and crow's feet. Filler occupies space and suits hollows and lost projection. A line that is there when your face is still is a skin or volume problem, and toxin will not remove it.
Many faces have both kinds of change, and the examination at rest and in movement sorts one from the other. The comparison of toxin and fillers sets the two side by side. Lines under the eye are covered on the under-eye lines page.
Can botulinum toxin be combined with other treatments?
Yes, when each treatment does a different job. Toxin reduces movement; it adds no volume and does not tighten skin. The plan sets which treatment goes where, and in what order.
| Paired with | Its job | How it fits |
|---|---|---|
| Dermal filler | Volume and structure, such as a fold over a hollow | Can be given on the same day in different areas, once the plan is clear |
| Skin remodelling | Lines already etched at rest | Planned separately, because toxin does not change them |
| Skin boosters | Crepey or etched skin, including on the neck | Neck plans may pair boosters with toxin for bands |
| Energy-based lifting | Laxity, which toxin cannot tighten | Neck bands are assessed for toxin rather than heat |
| Time Freeze Laser | Lifting and skin work using heat | Some plans combine the two, sequenced to avoid over-treatment |
Who is botulinum toxin suitable for?
It tends to suit dynamic lines from frowning, raising the brows or squinting. It may also suit downturned mouth corners or neck bands where muscle is the cause, and lower-face width or shoulder bulk where muscle is the reason and contour is the goal. It is a fair choice if you want to soften muscle activity while keeping your expression. It is a poor choice if your main concern is a line that stays when your face is still, loose skin, or a loss of volume. The consultation sorts one from the other, and the written plan includes doing nothing. If a line has both a muscle part and an etched part, BTX can only address the first, and the second is assessed separately.
What decides whether botulinum toxin is right for you?
Whether it is worth having is a question of fit, not price. The examination answers these questions.
| Question | Points towards toxin | Points elsewhere |
|---|---|---|
| What makes the line? | It deepens when you frown, raise your brows or squint | It shows at rest: skin remodelling or filler |
| What makes the width or bulk? | Muscle, such as the masseter on clenching | Bone or fat: another plan. See jaw slimming |
| Can the forehead be relaxed? | The brows and lids hold up without help from the forehead | A forehead holding heavy lids open: a lighter dose, or a plan for the lid |
| What do you expect? | A temporary softening that may be repeated | Volume, tightening or a lasting change |
| Any reason to wait or avoid? | None found at assessment | Pregnancy, breastfeeding, a neuromuscular disorder, a known allergy to a botulinum toxin product, or infection at the injection sites |
Botulinum toxin Singapore: who should avoid it
Pregnancy, breastfeeding, or planning a pregnancy. Active infection or inflammation at the injection sites.
A neuromuscular disorder such as myasthenia gravis, or a known allergy to a botulinum toxin product or its components.
Medicines that affect neuromuscular transmission. A bleeding disorder, or blood-thinning medicine.
Limits: what it cannot do
Lines that remain at rest are referred for skin remodelling or filler after assessment.
It is not a filler. Hollows and flat areas need another plan.
Droop from the lid muscle or heavy skin is referred to an oculoplastic or plastic surgery specialist.
The effect fades at a pace that differs between people and with the dose. No duration is promised.
If a muscle is affected that should not be, the effect is temporary, but it cannot be reversed at will.
How should I prepare for botulinum toxin?
Most of the preparation is information the doctor needs before setting a dose.
How long does the visit take, and does it hurt?
No set time is quoted, because the visit is built around examining your muscles before anything is injected. The injections themselves are a series of small points placed with a very fine needle.
Most people describe a brief sting at each point, a sense of pressure between the brows and very little at the crow's feet. Small raised bumps at each point usually flatten before you leave, and there is no wound to dress. How it feels varies between people and areas.
How soon does botulinum toxin work, and what if I stop?
The effect builds over days, not on the chair, and it fades as the nerve signal to the muscle recovers. No duration is promised, and results vary.
| Stage | What happens | What it means for you |
|---|---|---|
| On the day | No visible change yet; the small bumps flatten quickly | Nothing on the first day is the result |
| The following days | The treated muscle quietens in stages, one side sometimes ahead | Early unevenness is common and is not a reason to add more early |
| At review | The live examination is repeated in person | A small balancing dose if needed; the timing of any repeat is set |
| As it wears off | The nerve grows new connections and movement returns gradually | Expected, and not a sign that treatment failed |
| If you stop | Muscle activity returns once the effect has worn off | You can stop at any time; lines etched at rest need a different plan |
Aftercare
What are the side effects of botulinum toxin?
Small bruises, tenderness and a mild headache, which usually settle.
Asymmetry, a heavy brow or eyelid if a neighbouring muscle is affected, a change in smile, or tired chewing after jaw treatment. These are temporary.
Widespread weakness, or difficulty swallowing or breathing. This needs urgent care.
A bothersome drooping eyelid or brow, rash, facial swelling, worsening pain or signs of infection at a site, or marked asymmetry of the smile.
Double vision, or difficulty breathing or swallowing.
Placebo-controlled trials have found that frown lines improve more often than with placebo, and that side effects are uncommon but somewhat more frequent. Assessment and conservative dosing reduce risk, but never remove it.
Is botulinum toxin safe, and how is it regulated in Singapore?
No medicine is free of risk, and botulinum toxin is controlled as a prescription-only medicine in Singapore. Products are registered with the Health Sciences Authority. It is injected by a doctor registered with the Singapore Medical Council, in a licensed clinic, after a documented consultation. Ask for the product name and dose, and have both recorded in your notes. The guide to aesthetic medicine regulation explains who oversees what.
A 2015 meta-analysis of seven placebo-controlled trials with 1,474 people found frown lines responded far more often with toxin than with placebo, with no significant difference in how often adverse events occurred. [5] Its conclusion concerned one fixed dose for frown lines, and units differ between products.
A 2025 meta-analysis of 20 randomised trials, with 7,275 people treated and 2,552 given placebo, found adverse events somewhat more frequent with toxin, though the authors described their incidence as low. [6] Neither study predicts your own response, and results vary.
How much does botulinum toxin cost in Singapore?
Fees are not published here. A written quote is given at consultation, after Dr Sin Yong has assessed you. It depends on the areas treated, the dose each muscle needs, the formulation chosen, and whether BTX is combined with another treatment. The consultation also decides whether treatment is advised at all.