Written and medically reviewed by Dr. Kamen Ng. Last reviewed 2026-11-11. 18 min
By Dr. Kamen Ng · Head of Aesthetic Medicine, AOKLINIK
Two patients ask me the same question in opposite ways. One wants to know whether the brand I use is the best one. The other wants to know how many units she can get for her money.
Both have been pointed at the wrong variable, and this article is mostly about why.
A note on the word first. "Botox" is a brand name that has become shorthand for the whole category, in the way people say Panadol. There are several botulinum toxin products, they are genuinely different from one another, and the differences matter in ways the shorthand hides. So I will say botulinum toxin throughout.
What it actually does
Nerves tell muscles to contract by releasing a chemical messenger, acetylcholine, across the gap between nerve ending and muscle. Botulinum toxin type A blocks that release. The muscle receives no instruction and so does not contract.
Three consequences follow from that single mechanism, and understanding it tells you most of what the treatment can and cannot do.
It is temporary. The nerve terminal recovers and forms new connections, which is why the effect wears off over months rather than being permanent.
It is local. It works on the muscles it reaches. Precision is therefore everything, and unwanted effects are almost always a matter of the product reaching a muscle you did not intend.
It only works on muscle. If your concern is not caused by muscle activity, this is the wrong treatment, and a great deal of patient disappointment comes from that mismatch.
What it can treat, and what it cannot
Lines caused by movement
Glabellar lines between the brows, forehead lines, and the lines at the outer corners of the eyes. This is the core use and it is where satisfaction is highest.
The important distinction is between a line that appears when you move and a line that is there when your face is completely still. Movement lines respond well. A line etched into the skin at rest is a skin problem as much as a muscle one, and toxin will soften it rather than remove it. Treating movement lines before they etch is the genuine preventive argument for starting earlier, and it is the only one I find persuasive.
Position and shape
This is the part patients know least about and it is often where the biggest change comes from.
Brow position, by weakening the muscles that pull the brow down so your own elevator muscle raises it. I have written about that approach in detail in the article on the AO Crown Lift.
Downturned mouth corners, by treating the muscle that pulls them down. Chin dimpling and puckering. A gummy smile. A slight outward roll of the upper lip. Neck bands, and definition along the jaw where the neck muscle is pulling against it.
None of these are wrinkle treatments. They are changes in how the face sits and moves, and they are frequently what a patient is actually describing when they say they look tired or stern.
Muscle bulk
The jaw muscle can be reduced in size with repeated treatment, which narrows the lower face in patients whose width is muscular rather than skeletal. It also helps clenching and grinding, which is why some patients come for one reason and stay for the other.
The distinction matters: if your lower face is wide because of bone, this will not change it, and that is determined by examination rather than by what you have read.
Sweating
Excessive underarm sweating responds well and the effect lasts longer than it does on facial muscles. In this climate it is one of the treatments patients are most grateful for, and it is a genuinely medical rather than cosmetic indication.
What it cannot do
It does not replace lost volume. It does not tighten loose skin, and in a face with significant laxity it can make heaviness more apparent rather than less. It does nothing for pigmentation, for texture, for pores, or for scarring. It will not lift a face that has descended through loss of structural support.
If someone has offered you toxin for any of those, they have either misunderstood your problem or are selling you the treatment they had available.
Is all botulinum toxin the same?
No, and the differences are real. Here are the three most established products, by their proper names.
| Nonproprietary name | Complexing proteins | Molecular size | Storage before use |
|---|---|---|---|
| onabotulinumtoxinA | Present | 900 kDa complex | Refrigerated |
| abobotulinumtoxinA | Present | Mixed, commonly cited around 300 kDa | Refrigerated |
| incobotulinumtoxinA | None | 150 kDa neurotoxin only | Room temperature |
Several newer products exist, including formulations designed for longer duration and liquid presentations that need no reconstitution. The principles below apply to all of them.
The single most important thing to know
A unit of one product is not a unit of another. Units are defined by each manufacturer's own laboratory assay, which means they are proprietary measures and direct potency comparison between products is not valid.
In practice, roughly two to three units of abobotulinumtoxinA correspond to one unit of onabotulinumtoxinA, often quoted as about 1 to 2.5, while onabotulinumtoxinA and incobotulinumtoxinA are generally used at approximately 1 to 1. Those ratios are approximations drawn from comparative work, not official equivalences, and no manufacturer endorses a conversion.
So "50 units" is a meaningless quantity unless you know which product. This matters commercially, because patients compare clinics on units. A clinic quoting a large number of units of one product may be giving you less actual effect than a clinic quoting a smaller number of another, at a higher price, while appearing more generous.
If you are comparing quotes, ask which product and how many units of that product. Anything else is comparing two different currencies without an exchange rate.
What "highly purified" means
This is a real pharmaceutical distinction, and it is also a marketing phrase, so let me separate the two.
The science
Botulinum toxin is produced naturally as a complex. The active neurotoxin, which is about 150 kDa, comes bound to accessory proteins that have no therapeutic action of their own. Most products are supplied as that complex. One is manufactured with the accessory proteins removed, leaving only the active neurotoxin.
The argument for removing them concerns immunogenicity. Proteins introduced into the body can provoke an immune response, and if your immune system produces neutralising antibodies against the neurotoxin, the treatment stops working. That is called secondary non-response.
There is reasonable support for the argument. In animal work, the complex-free preparation did not produce neutralising antibodies after repeated injection where the complexed products did, and one of the accessory proteins appears to act as an adjuvant, meaning it amplifies the immune response to whatever it accompanies.
In patients, neutralising antibodies with long-term use of the complexed products have been reported in something like 0.3 to 6 per cent, varying considerably with the indication and the dose. In one prospective series of cervical dystonia patients switched to the complex-free product and followed for four years, antibody titres did not rise, fell below baseline in most, and a majority became seronegative.
Now the honest part
Those antibody figures come mainly from therapeutic medicine, not aesthetics. Conditions like cervical dystonia and spasticity are treated with doses many times larger than anything used on a face, and antibody formation tracks dose. At aesthetic doses the problem is uncommon.
The clinical significance in aesthetics is not established. The major review I have drawn on states plainly that a definitive need for the absence of these proteins in either therapeutic or aesthetic use has not been demonstrated. It raises the reasonable possibility that it could matter more for someone treated frequently over decades, which is a hypothesis about the future rather than a current finding.
And the main review arguing the purity case was written by the head of botulinum toxin research at the company that makes the purified product. The science in it is sound and I use it. You should still know who wrote it, and I would rather tell you than have you find out.
I should also disclose that I have attended training delivered by that manufacturer, as have most injectors of my generation. It does not determine what I use, and you are entitled to know it.
What I actually take from all this
Two things, and the second is more useful than the first.
The purity argument is plausible, mechanistically coherent, supported preclinically, and unproven where it would matter most to you. It is a reasonable factor among several rather than a reason to dismiss other products, all of which are effective and well characterised.
The genuinely useful conclusion is the one both sides of this debate agree on, and it is the same advice that follows whichever product you use: the lowest effective dose, at the longest acceptable interval. That is the recommendation in the purity literature itself. It is also, by coincidence or not, exactly what produces a natural-looking result.
There is one practical point worth adding for Malaysia. The complex-free product is stable at room temperature before reconstitution rather than requiring refrigeration. In a hot climate, with the possibility of power interruption, a product whose potency does not depend on an unbroken cold chain has something real to recommend it. That is a logistics argument rather than a clinical one, and it is not nothing.
How to choose, honestly
Patients expect me to name a winner. The honest answer is less satisfying and more important.
The injector matters more than the product. All the established products work. None of them decides where the needle goes, how deep, in what pattern, at what dose, or whether the muscle being treated is the one causing your problem. Those decisions produce almost all of the difference between a good result and a bad one, and no product compensates for getting them wrong.
I can produce a poor result with any product on this list. I cannot produce a good result with a well-chosen product and poor judgement about your anatomy.
What is worth asking, in order:
Is this a licensed medical facility, and is the person injecting me a registered medical practitioner? Which product is being used, by name, and is it registered for use in Malaysia? How many units of that product, and why that number for me? Who do I contact if something is not right, and will I be reviewed?
What is not worth asking: which brand is best. If a clinic's main argument is their brand rather than their assessment of your face, you have learned something about the clinic.
Is more units better?
No, and this is the belief I spend most time correcting.
Dose determines how much a muscle is weakened and, within limits, how long the effect lasts. Below the effective dose you get an inadequate result. Above it, here is what you actually buy.
Loss of expression. The aim is a weaker muscle, not an absent one. Past a certain dose the muscle stops participating in your face, and that is the frozen look people recognise. It is not a different treatment from a natural result. It is the same treatment, overdosed.
A heavy brow. Over-treating the forehead weakens the only muscle holding your brow up. Patients describe this as heaviness, and it is the commonest route to an upper face that looks worse after treatment than before.
Compensation. Shut down one muscle completely and neighbouring muscles take over the expression, sometimes producing new lines in new places. The face finds a way.
No proportionate gain in duration. You do not get double the months for double the dose.
And a larger cumulative protein load over the years, which is the one argument from the immunogenicity literature that applies to you directly, whichever product you use. More dose, more often, over decades, is the pattern that carries whatever risk exists.
The correct dose is the smallest one that achieves the goal, and it is not a number I can publish, because it depends on which muscle, how strong it is, what you want to keep, and what product. Men generally need more than women for the same effect, because the muscles are larger, and I have covered that in the article on male treatment.
For a first-time patient I deliberately dose low and review at two weeks. Adding is straightforward. Waiting out too much is three or four months of looking like somebody else, and no amount of apology shortens it.
A word about prescription medicine, because it matters here
Botulinum toxin is a prescription medicine. It must be assessed, prescribed and administered by a registered medical practitioner, in a licensed healthcare facility, using a product registered for use in Malaysia.
This is not a formality and the local market gives it teeth.
Unregistered product is a real problem. Toxin brought in outside the registration system, with no verified cold chain and no accountable local distributor, is in circulation. You cannot tell by looking at a vial, and the price is usually the clue.
Non-medical injectors are a real problem. This is a prescription medicine being injected adjacent to the eye, into muscles whose function you need. The appropriate person to do that is a registered doctor who assessed you first.
A very cheap price is information. The product has a floor cost. A price well below it means either a product you should ask about, a dilution you should ask about, or an injector you should ask about. We publish our prices openly so that you have something to compare against.
The short version
Botulinum toxin blocks the signal from nerve to muscle. It therefore treats things caused by muscle movement: expression lines, muscle bulk, the position and behaviour of features, and sweating. It does not replace volume, tighten skin, or improve pigment or texture.
The products are genuinely different and a unit of one is not a unit of another, because units are each manufacturer's own measure. Comparing clinics on unit counts without naming the product compares nothing.
Highly purified means the accessory proteins have been removed, leaving the active neurotoxin. The immunogenicity argument for that is mechanistically sound and preclinically supported, the clinical significance at aesthetic doses is unproven, and the main review making the case was written by an employee of the manufacturer concerned.
More units is not better. Past the effective dose you buy lost expression, a heavier brow, compensation by neighbouring muscles, no proportionate extra duration, and a larger cumulative load over the years.
The injector matters more than the product, and the advice that follows from every side of the purity debate is the same: the lowest effective dose, at the longest acceptable interval.
It is a prescription medicine. It belongs in a licensed facility, given by a registered doctor, using a product registered for use in Malaysia. A price well below the market is information rather than a bargain.
Book a consultation
If you are not sure whether what bothers you is caused by muscle movement at all, that is the most useful question to bring. A fair number of patients who ask for anti-wrinkle injections need something else, and some need nothing.
Book a consultation with Dr. Kamen Ng at AOKLINIK Penang.
References
- Pharmaceutical, biological, and clinical properties of botulinum neurotoxin type A products. Drugs in R&D. 2014 link.springer.com
- Clinical relevance of botulinum toxin immunogenicity link.springer.com
- Immunogenicity of botulinum toxin type A in different clinical and cosmetic treatment: a literature review pmc.ncbi.nlm.nih.gov
- Cross-induction of anti-complexing antibodies in patients treated with botulinum toxin formulations containing complexing proteins. Toxins mdpi.com
- IncobotulinumtoxinA: a highly purified and precisely manufactured botulinum neurotoxin type A. Journal of Drugs in Dermatology jddonline.com
- Applied anatomy for botulinum toxin injection in cosmetic interventions. Current Otorhinolaryngology Reports. 2020 link.springer.com
Frequently asked questions
Not if it is dosed and placed properly, and that is the honest condition rather than a reassurance. The frozen look is not what this treatment does. It is what too much of it does. If you tell me at the consultation that looking untreated matters more to you than maximum smoothing, it changes the dose, so say it.
Common and minor: small bruises, a headache for a day or two, tenderness at the injection points. The ones worth understanding properly: a drooping upper eyelid, which happens if product reaches the muscle that holds the lid up, and which resolves as the effect wears off but can take weeks to months. A heavy or dropped brow from over-treating the forehead. Asymmetry, which is usually correctable at review. An oddly peaked brow if the outer part of the forehead muscle is left untreated while the middle is weakened. Dry or irritable eyes, and incomplete eye closure, with treatment around the eyes. Uncommon: the treatment not working, including through antibody formation with long-term use. Rare: spread of effect beyond the injection site causing swallowing or breathing difficulty, which is associated with high therapeutic doses rather than aesthetic ones but is the reason this is a prescription medicine administered by a doctor. Our complications article covers management in more detail.
Anyone pregnant or breastfeeding. Anyone with a neuromuscular condition such as myasthenia gravis, Lambert-Eaton syndrome or motor neurone disease. Anyone with an infection at the injection site, or a known hypersensitivity. Certain antibiotics interact with it. There are also patients I decline for aesthetic rather than medical reasons, usually because what they are asking for would not suit them. Tell me your full medical history and medication list, including supplements. It changes decisions.
Onset is typically a few days, with the full effect around two weeks, which is why I review then rather than earlier. Duration on facial muscles is commonly three to four months, varying with the area, the dose, the product and the individual. The jaw muscle and underarm sweating both tend to last longer. Nobody can tell you your number in advance, and anyone who does is guessing.
For most people, no. A minority develop antibodies that neutralise it, which is more likely with higher doses given more frequently, and is therefore more a feature of therapeutic medicine than aesthetics. The way to reduce that risk is the same advice as everything else here: the lowest effective dose, at the longest interval you find acceptable.
It has been in clinical use for decades across a wide range of conditions, including at doses far above anything cosmetic, and the long-term safety record is reassuring. The thing I would watch over decades is not safety but drift: a slow increase in dose and frequency that nobody ever steps back and reviews. That is a habit rather than a hazard, and it is avoidable.
No. If you stop, the muscle recovers and your face returns to its natural course. It does not become worse than it would have been. Repeated treatment of the jaw muscle does reduce its bulk over time, which is the intended effect there rather than a side effect.
It wears off, which is the genuine advantage of this treatment over anything that cannot be reversed. If the problem is too little, I can add at review. If it is too much, we wait, and I will tell you honestly how long. I would rather have that conversation having under-treated you than over-treated you, which is why I dose conservatively the first time.
Often, and sequencing is a clinical decision rather than a convenience one. What I will not do is combine everything at a first visit, because if something needs adjusting I want to know which thing caused it.
Standard advice is to stay upright for a few hours, avoid rubbing or massaging the treated area that day, and leave strenuous exercise, saunas and hot yoga until the following day. Alcohol and blood-thinning supplements increase bruising if taken beforehand.