Excessive sweating is a medical condition with a name, a severity scale and an approved treatment behind it. It isn’t a hygiene problem and you shouldn’t have to manage it with a spare shirt in your bag. Two minutes here will tell you whether you qualify.
Health Canada approves botulinum toxin for excessive sweating at one site only, the underarms, at 50 units per side. Palms, soles, forehead and scalp are off-label. That distinction decides how long each area stays dry and what trade-off comes attached, so it belongs in the conversation before you choose an area.
| Area | Status in Canada | What the published data shows | What to plan for |
|---|---|---|---|
| Underarms | Health Canada approved for severe primary axillary hyperhidrosis, 50 units per side in the product monograph | 91% of patients had at least a 50% reduction in sweat production by week four | Median duration of response about 201 days, roughly 6.7 months, typically four months to a year |
| Palms | Off-label. The manufacturer never filed for the site, but there are decades of published use | Around 82% improvement at two weeks and roughly 74% at three months, tapering after that | A temporarily weaker pinch grip. Nerve conduction studies measured meaningful drops at around three weeks, returning close to normal by roughly nine months |
| Soles, forehead and scalp | Off-label | Outside the Canadian approval, which covers the underarms only | A shorter run than the underarms give you, so budget for more frequent visits |
A 3 or a 4 on the Hyperhidrosis Disease Severity Scale is the range where injecting is appropriate, and four honest weeks of clinical-strength aluminum chloride antiperspirant applied at night to dry skin comes first. Sweating that began suddenly in adulthood, covers the whole body, or wakes you at night is referred to your family doctor rather than injected, because treating it would hide the signal.
Is this hyperhidrosis, or do you just sweat a lot?
Everyone sweats. Hyperhidrosis is sweating far beyond what your body needs to cool itself, and it has a recognisable pattern: it shows up in specific areas rather than all over, it’s usually symmetrical, and it stops while you’re asleep. Primary hyperhidrosis means there’s no underlying illness causing it. It typically starts in childhood or the teenage years and often runs in families.
Clinicians grade it with the Hyperhidrosis Disease Severity Scale. Score yourself honestly. My sweating is:
- 1. Never noticeable and never interferes with daily activities.
- 2. Tolerable but sometimes interferes.
- 3. Barely tolerable and frequently interferes.
- 4. Intolerable and always interferes.
A 1 or a 2 is mild and probably doesn’t need injecting. A 3 or a 4 is the range where botulinum toxin is appropriate, and it’s also where Health Canada’s approval for the underarms sits.
You’re not unusual. The largest recent survey put the prevalence at 4.8% of the population, with the underarms the most commonly affected site at around 65%. Roughly seven in ten people who have it describe their sweating as severe in at least one area. So it’s common, and most people who have it have it badly.
What we ask you to try before we inject anything
Clinical-strength antiperspirant containing aluminum chloride, applied at night to completely dry skin, then washed off in the morning. Not applied after a shower, not applied to damp skin, not applied in the morning. Most people who tell us antiperspirant didn’t work were using it the way you use deodorant, which is the wrong way and the reason it stung and failed.
Give that four honest weeks. If it still doesn’t hold, that’s a real clinical finding, and it’s exactly what the approval language means when it says patients unable to get relief from antiperspirants. We’re not going to pretend the drugstore route works for everyone. It just needs ruling out first.
Underarms: the version with an approval behind it
Health Canada has approved onabotulinumtoxinA for severe primary axillary hyperhidrosis in patients who can’t get relief from antiperspirants. The dose in the product monograph is 50 units per underarm.
The numbers from the registration trial are unusually good for anything we inject. Of patients treated at 50 units per side, 91% had at least a 50% reduction in sweat production by week four. Median duration of response was about 201 days, roughly 6.7 months, with a typical range of four months to a year. That’s considerably longer than cosmetic treatment lasts, which surprises almost everyone who books it.
The injections are shallow and intradermal, a grid of small points spread across the sweating area rather than a few deep placements. Before we start we can map the active zone with Minor’s starch-iodine test, which stains actively sweating skin dark so we treat where you actually sweat instead of where we assume you do. It takes a few extra minutes and it’s the difference between covering the zone and covering the armpit.
Palms, soles, face and scalp: off-label, and here’s the trade-off
The Canadian approval covers the underarms only. Palms, soles, forehead and scalp are off-label. Off-label doesn’t mean unstudied, it means the manufacturer never filed for those sites. Palms in particular have decades of published use.
They work. Published series report improvement around 82% at two weeks and roughly 74% at three months, tapering from there, so you’re looking at a shorter run than the underarms give you.
Now the part you should hear before you book rather than after. Toxin injected into the palm can reach the small muscles of the hand. Nerve conduction studies measured meaningful drops in the muscles that move the thumb and the little finger at around three weeks, returning close to normal by roughly nine months. In practice that reads as a temporarily weaker pinch grip. It’s reversible. It’s also real, and if you play an instrument, do fine handwork or lift seriously, it’s worth planning around rather than discovering.
Palms also need proper freezing. Underarm treatment is genuinely easy. Palms aren’t, and anyone telling you otherwise hasn’t done many of them.
From our injection team: the underarm appointment is one of the simplest things we do and it changes more about a person’s week than most of what we inject. People come back and talk about interviews and dates, not about looking younger. Palms are the opposite. Harder to freeze, harder to dose, and we spend more of the appointment on the grip conversation than on the injecting.
When we decline
Sweating that began suddenly in adulthood, happens over your whole body rather than in defined areas, wakes you at night, or arrives alongside weight loss, fevers or a racing heart is not the pattern of primary hyperhidrosis. That picture points at secondary causes: thyroid, medications, infection and others. We’ll send you to your family doctor to have it worked up rather than inject you, because treating the sweat would hide the signal.
We also don’t treat during pregnancy or breastfeeding, where there’s an active infection at the injection site, or where there’s a neuromuscular disorder that makes toxin a poor idea.
Benefits, receipts and what it costs you
This is one of the few things we do that a benefits plan will often help with, because it’s a recognised medical indication rather than an elective cosmetic one. Health spending accounts and some extended health plans reimburse RN-administered treatment when the paperwork is right. OHIP does not cover it and we don’t bill OHIP.
We issue a receipt carrying the nurse’s regulatory number, the product DIN and the medical indication written out, which is what an HSA administrator actually needs to process a claim. We can’t promise your plan pays. We can promise the paperwork won’t be the reason it doesn’t. Bring your benefits card to the consultation and we’ll tell you what to expect.
Current pricing sits on the Toronto price index, which rebuilds from our live booking system, and you get an exact quote at consultation. Underarm treatment uses considerably more product than a cosmetic area, so price it against how long it lasts rather than against a forehead appointment.
Questions
How long before it works?
Sweating starts dropping within two to four days and has fully settled by about two weeks.
Will I just sweat somewhere else instead?
Compensatory sweating is a well-documented problem after surgical sympathectomy, where a nerve is cut. It isn’t a feature of toxin treatment, because you’re quieting a patch of skin rather than severing anything.
Does it stop the sweating completely?
No, and you wouldn’t want it to. The goal is bringing an area back to normal output, not switching it off.
How often will I need it?
Most people come back once or twice a year for underarms. Palms run shorter, so plan on more often.
Is it the same product as cosmetic Botox?
Same molecule. Different depth, different target, and a much larger dose spread over a much wider area. That’s why it costs more per session and lasts longer. You can read how the medical uses differ on our medical Botox page, and how standard treatment works on our Botox page.
If you’ve scored yourself a 3 or a 4 and antiperspirant has already failed you, you’re the patient this treatment was approved for. Book the free consultation at our Fort York clinic and we’ll map the area, talk through underarms versus palms, and give you an exact quote. Book online or call 416-923-1200.
Ready to look into it properly?
Our consultation is free. We will look at your skin, give you an honest recommendation, and say so if a different treatment would suit you better.
Or call 416 923 1200 · 46 Fort York Blvd, CityPlace, Toronto
Questions about this treatment?
Ask us anything before you book. Consultations are free, and we will tell you honestly if a treatment is not right for you.