Botulinum toxin:
what to expect, from mapping to the review

What happens before botulinum toxin is injected?

Before any botulinum toxin is placed there is a consultation, and it decides whether muscle is the cause of what you see. A line made by frowning, raising the brows or squinting softens when the muscle is quietened; a line already etched at rest does not, and needs skin remodelling or filler instead, which is explained at the visit rather than discovered afterwards. Dr Sin Yong takes a history that covers medicines affecting neuromuscular transmission, bleeding tendency, pregnancy and breastfeeding, and any earlier toxin treatment: the product, the areas and the dates, because units are specific to each formulation and cannot be converted between brands.

You leave with a written plan naming the zones, the formulation and the review, with the option of no treatment. Who suits it and who should wait is on the botulinum toxin page, and the common follow-up questions are on botulinum toxin questions.

How are the muscles mapped before injection?

On the day the examination is live, because photographs at rest show almost nothing in these areas. The upper face is examined at rest, on a full brow raise, in a frown, and with the eyes closed and then reopened; the jaw is examined on clenching and neck bands on straining. Which muscles are recruited, how strongly, and how high up the forehead the frontalis is active decide where each small dose is placed and how much each point receives.

Brow position and lid reserve are read before the forehead is relaxed. The brow is checked against the bony rim of the eye socket and the upper lids are checked for skin that would land on the lashes once the frontalis stops helping; a forehead that is holding heavy lids open is dosed conservatively, or the plan is redirected to the lid. The glabella is usually treated with the forehead so that the brows are not pulled down once the frontalis is quieter, as the forehead and frown lines page explains. Asymmetry is mapped, not averaged: one brow habitually higher, or a jaw bulkier on the chewing side, gets a side-by-side plan rather than identical doses. The points are then marked on the skin.

“I watch the muscle work before I dose it, and I do not dose for the day you leave. The face I am treating is the one that appears once the signal has faded, and I see that one at review.”

Dr Sin YongOn how botulinum toxin is mapped and reviewed

What does the injection itself involve?

The skin is cleaned and, where a zone is sensitive, a cool pack or a topical anaesthetic is used; many people have the upper face treated without either. The formulation chosen for the zone is prepared. Dr Sin Yong places small volumes into each marked point with a fine needle: a brief sting per point, a sense of pressure in the frown complex, and very little over the crow's feet. The depth changes with the muscle: superficial over the thin orbicularis at the eye corner, deeper into the corrugators and the masseter.

A small raised bump appears at each point, which is the volume of liquid rather than the medicine working, and it flattens within the hour. Nothing else is visible, and nothing has changed in the muscle yet. You are asked not to rub, massage or press the areas, to stay upright for the next few hours, and to leave strenuous exercise, heat and alcohol for the day. The first hours and days are set out on anti-wrinkle injection aftercare.

How does the effect come on after botulinum toxin?

The effect is not visible on the chair, and that is expected. Botulinum toxin works by reducing the nerve signal to the muscle it was placed in, and that signal fades gradually rather than switching off, so the muscle quietens in stages over the following days: first a sense that the frown does not quite reach its usual depth, then a visible softening of the line on expression, then the settled effect. One side is sometimes ahead of the other, and a stronger muscle lags a weaker one, which is why early asymmetry is watched rather than corrected on the spot.

In the jaw the sequence is slower and felt before it is seen: chewing feels less forceful first, and the change in bulk follows as the masseter is used less. Nothing about the onset is a reason to add dose early, and nothing on the first day should be read as the result. A heavy brow or a drooping eyelid, if it happens, is assessed rather than waited out without advice. Difficulty swallowing, speaking or breathing, generalised weakness, or double or blurred vision are rare, can appear hours to weeks after injection, and need emergency care; the signs are on complication care.

What happens at the botulinum toxin review?

Dosing starts conservatively, so the review is where the response is read and anything outstanding is balanced. It is timed individually once the medicine has taken effect and is done in person; if that review would fall after a visitor has left Singapore, the plan is staged differently or deferred, as the overseas patients page explains. Dr Sin Yong repeats the live examination: brow raise, frown, eyes closed and reopened, jaw clenched. A small balancing dose corrects early asymmetry; a bulge at the jaw angle from an untreated layer of the masseter is addressed; and a brow that has dropped is managed rather than added to.

The review is also where the timing of any repeat is decided. No duration is promised, because the effect fades at a pace that differs between people and with the dose, and a repeat is timed to the muscle returning rather than to a calendar. Whether a line that remains at rest now needs a different tool, such as skin remodelling or a filler, is decided here too; the distinction is explained on the botulinum toxin cost factors page without figures, and the jaw-specific sequence on jaw BTX and face slimming.