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The sentence I say most often about sweating is that it is a medical condition, not a nerves problem and not a hygiene problem. Most people who come in have been told at some point to relax, and they have usually worked out for themselves that this is backwards. The sweating comes first. The dread of it coming on in a meeting, a handshake, or a first date is a reaction to it, not the cause.
The second thing I repeat is duller but changes more outcomes. Almost everyone who tells me antiperspirants do not work for them has been using them the way the packaging suggests: in the morning, straight after a shower, on damp skin. That is close to the worst way to use one. Antiperspirants need to go on completely dry skin at night, when sweating is at its lowest, so the active ingredient can settle into the duct. Before we talk about injections or tablets, I want that tried properly for two weeks.
The last thing is a boundary. Sweating that has come on suddenly in adulthood, that covers the whole body, or that wakes you soaked at night is a different problem from the kind that starts in childhood on the palms and underarms. That version needs a look for a cause rather than a stronger antiperspirant.
— Dr. Schwarz, Board Certified Dermatologist
What It Is
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Hyperhidrosis means sweating beyond what the body needs for cooling. Skin has millions of small sweat glands, called eccrine glands, and they are packed most densely in the palms, soles, underarms and face. Nerves from the sympathetic nervous system tell those glands when to switch on. In hyperhidrosis the glands themselves are normal. The signal reaching them is turned up.
It comes in two forms, and telling them apart is the first thing a doctor does.
Primary focal hyperhidrosis is the common one. It affects specific areas - most often the underarms, palms, soles, face and scalp - usually in a matching pattern on both sides. It tends to start in childhood or around puberty, it often runs in families, and it stops during sleep. There is no underlying illness driving it. The wiring is simply set high.
Secondary hyperhidrosis is sweating caused by something else: a medicine, an overactive thyroid, a hormonal shift such as menopause, low blood sugar, an infection, a nerve injury, or less often something more serious. It usually looks different. It tends to affect the whole body rather than a few areas, it can happen during sleep, and it often starts in adulthood rather than childhood.
The impact of the primary form is easy to underestimate from the outside. Palms that drip make handwriting, tools, phones and handshakes difficult. Underarm sweat ruins clothes and dictates what people wear and where they sit. Wet feet cause slipping, foot odor and repeated fungal infections. Surveys consistently find that people with hyperhidrosis rate its effect on daily life alongside conditions that are treated far more aggressively.
Key Facts
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| How common | Estimates put it at roughly 3 to 5 percent of people, and most of them never raise it with a doctor |
| Who gets it | Primary hyperhidrosis usually starts in childhood or the teenage years, affects both sides equally, and often runs in families |
| Curable or managed | Managed - treatment controls it well, but sweating returns when treatment stops |
| Prescription needed | Not always. A strong antiperspirant used correctly is enough for a fair number of people |
| Time to improve | About one to two weeks for antiperspirants, a few days to a week for botulinum toxin injections |
Symptoms
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Underarm
Hands and Feet
Whole-Body or New
How It Looks by Skin Tone
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Sweat glands work the same way across skin tones, and hyperhidrosis is not more or less common in deeper skin tones. What differs is what happens to the skin around the treatment.
The most practical issue is irritation from strong antiperspirants. Aluminum chloride is acidic and can leave the underarm red, stinging and flaky. On deeper skin tones that inflammation frequently heals into a flat brown, gray or violet patch, called post-inflammatory hyperpigmentation, which takes months to fade. So underarm darkening often gets blamed on the antiperspirant itself. Usually the aluminum is not staining anything - the irritation is, along with shaving, friction from clothes and rubbing. Fixing the irritation, rather than stopping treatment outright, is normally the answer: apply to fully dry skin, drop to every second or third night, and do not apply on the night you shave. The second issue is that irritated skin is harder to read. Redness on deeper skin tones can look brown, gray or violet rather than pink, so a sore, macerated underarm or a rash in a skin fold is regularly judged as milder than it is, and treated later than it should be. A small practical point in the other direction: the starch-iodine test, which maps where sweat is coming from, turns dark blue-black wherever the skin is wet. It reads the same on every skin tone. If a procedure is on the table - botulinum toxin, microwave treatment, or anything that inflames the skin - the same principle applies. The procedure works the same. The mark left behind if the skin gets inflamed lasts longer, so it is worth asking the person doing it how they handle that.
Where It Shows Up
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Causes
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Hyperhidrosis — Mechanism figure
Hyperhidrosis — Mechanism figure
Hyperhidrosis — Mechanism figure
Hyperhidrosis — Mechanism figure
The pathway is short and worth knowing, because every treatment interrupts it at a different point.
A signal starts in the part of the brain that regulates temperature and emotion. It travels down the spinal cord and out along the sympathetic nerves that supply the skin. At the sweat gland, the nerve releases a chemical messenger called acetylcholine. The gland responds by pushing sweat up its duct and out onto the surface. That final step is what you feel.
In primary hyperhidrosis, nothing along that chain is diseased. There are not more sweat glands than normal, and the glands are not abnormal. The signal is simply set too high, and it fires in response to ordinary things - a warm room, a mild nerve, a spicy meal - at a volume that most people's does not.
Because the trigger is a nerve signal rather than an injury or an infection, the sweating tends to switch off during sleep, when that part of the nervous system quiets down. That is one of the clearest ways to separate the primary form from sweating caused by something else.
Secondary hyperhidrosis works differently. There the signal is being driven by an outside cause - a medicine, a hormone, a fever, low blood sugar, a nerve that has been damaged or rerouted. Treating the cause usually settles the sweating.
Risk Factors
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Most of what determines whether you sweat this much is set before you have any say in it. The list below is a mix of things that raise the odds of the primary form and things that point toward a secondary cause.
Course
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Primary hyperhidrosis is a long-running condition with a fairly predictable arc.
Childhood | First signs: Sweaty palms and feet, often noticed as smudged homework, slippery hands in sport, or shoes that wear out fast. It is frequently mistaken for shyness.
Puberty to early twenties | Peak: Underarm sweating usually starts or worsens here, and this is when most people find it hardest. Clothing choices, social situations and career decisions often get shaped around it.
Twenties to forties | Steady: For most people it settles at a level that does not change much year to year. This is when most people finally seek treatment, often after a decade or more of managing alone.
Midlife and later | Gradual easing: Sweating often becomes somewhat less intense with age, particularly on the palms. It rarely disappears entirely.
Treatment does not change the underlying wiring, so the pattern here describes untreated hyperhidrosis. Antiperspirants, injections and tablets all control it well while they are being used, and sweating returns at its old level within days to months of stopping, depending on the treatment. Secondary hyperhidrosis follows the course of whatever is causing it, and often resolves when that is treated.
What Makes It Worse
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There are essentially four steps behind excessive sweating: (1) the nerve signal leaving the brain and spinal cord, (2) the chemical message arriving at the sweat gland, (3) the gland pushing sweat up its duct, and (4) the wet skin and everything that follows from it.
Different triggers push on one or more of these steps, making sweating heavier, more frequent, or more of a problem once it happens. The diagram below shows the four steps, and the number next to each line shows which step that trigger affects.
Why does this matter? Because the treatments work at different points in the chain, and so do the mistakes. An antiperspirant used on wet skin fails at step three no matter how strong it is, and no amount of stress management fixes that.
- Heat and humidity The ordinary trigger, and the one that makes summer the season people finally book an appointment.1
- Stress, anticipation and social pressure Exams, presentations, interviews and first meetings. In primary hyperhidrosis these produce sweating far out of proportion to the situation.1
- Dreading the sweating itself The most frustrating loop on this page. Worrying about visible sweat raises the signal that produces it, which is one reason treating the sweating often calms the worry.1
- Spicy food, caffeine, alcohol and nicotine All raise sweating, and spicy food in particular can trigger sweating on the face and scalp within minutes.1
- Some medicines Certain antidepressants, pain medicines and others increase sweating as a side effect. This is worth reviewing with your doctor rather than working around.12
- An untreated overactive thyroid Drives whole-body sweating that will not respond properly to anything applied to the skin.1
- Applying antiperspirant in the morning After a shower. The single most common reason a product is written off as useless. Damp skin and active sweat glands wash the active ingredient out of the duct before it can do anything.3
- Applying it to damp skin Even slightly damp. Not merely less effective. Aluminum chloride reacts with water and becomes more irritating, so wet skin gives you the sting without the benefit.34
- Shaving the underarm Then applying a strong antiperspirant the same night. Freshly shaved skin has small breaks in it, and this is the classic recipe for a burning, red underarm.4
- Stopping treatment The first time it stings. Irritation usually means the schedule needs easing, not that the treatment is wrong. Most people who stop here never come back to it.3
- Closed shoes and synthetic socks Worn all day. Trapped moisture leads to soft, white, macerated skin, foot odor, athlete's foot and small pitted patches on the soles.4
- Wearing the same pair of shoes every day Shoes need roughly a day to dry out fully, and damp shoes keep the cycle going.4
- Sitting in damp clothes After exercise or a commute. Prolonged wetness against skin causes rashes in the folds, particularly under the arms, under the breasts and in the groin.4
- Using a deodorant And expecting it to reduce sweat. Deodorant addresses odor. It does not block sweat at all.3
What Makes It Better
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There are essentially four ways to reduce sweating: (1) turn down the nerve signal, (2) block the chemical message at the gland, (3) block or shut down the gland itself, and (4) manage the wet skin so it causes fewer problems.
Different treatments and habits work on one or more of these four steps. The diagram below shows each step, and the number next to each line shows which step that treatment or habit affects.
Why does this matter? Because hyperhidrosis has a genuine treatment ladder, and most people never get past the first rung - not because it failed, but because it was used wrong. Working up the ladder in order saves a lot of time and money.
An aluminum-based antiperspirant, applied at night to bone-dry skin. The foundation of treatment, and the step most people skip past. Dry the skin completely, apply a thin layer, leave it overnight, wash it off in the morning. Do this nightly until sweating drops, then drop back to once or twice a week to hold it. [3]
Over-the-counter clinical strength versions. Sold alongside ordinary antiperspirants and considerably stronger. Worth trying before anything by prescription. [3]
- Prescription-strength aluminum chloride Stronger again, and the usual next step. Irritation is the limit on how often it can be used, so it is normally started every second or third night and spaced out further once it is working.3
- Glycopyrronium cloth for the underarms A prescription wipe used once a day that blocks the chemical message at the gland. Wash your hands after using it and keep it away from the eyes, because rubbing them afterwards causes blurred vision and a widened pupil.2
- Iontophoresis for hands and feet Hands or feet sit in shallow trays of water while a weak electrical current passes through. It is thought to temporarily block the sweat ducts. It takes several sessions a week to get going and then a maintenance session every week or two, and the machines can be used at home. It is one of the best options for palms and soles.3
- Botulinum toxin injections A grid of small injections blocks the chemical message where it reaches the glands. It is approved for severe underarm sweating, works within about a week, and typically lasts several months before it needs repeating. It is also used on palms, soles and the scalp, though palm injections are more uncomfortable and can cause temporary weakness in the hand.2
- Anticholinergic tablets Such as glycopyrrolate or oxybutynin. They block the same chemical message throughout the body, which is why they help sweating everywhere at once and why the side effects are what they are: dry mouth, blurred vision, constipation and reduced tolerance of heat. Often used at low doses, or only on days when it matters.2
- Microwave treatment of the underarm An in-office procedure that heats and destroys underarm sweat glands, with a lasting effect after one or two sessions. It involves swelling and soreness for a week or two afterwards.3
- Surgery to cut the sympathetic nerve Reserved for severe palm sweating that has not responded to everything else. It works reliably on the hands, but most people go on to sweat more heavily somewhere else instead, usually the trunk, and that is permanent and cannot be reversed. It belongs at the end of the ladder, not the middle.1
- Treating anxiety When it is part of the loop. Not a substitute for treating the sweating, but where dread of sweating has become its own problem, addressing both works better than either alone.1
- Absorbent underarm liners Undershirts and moisture-wicking fabrics too. They do not reduce sweat, but they change how much of it shows and how much clothing gets ruined.4
- Wicking socks and rotated shoes Wool or synthetic socks, two pairs of shoes, and antiperspirant on the soles. Antiperspirant works on feet as well as underarms, and most people have never tried it there.34
- The fungal infection or the odor Treated separately. Athlete's foot, small pitted patches on the sole and underarm odor are consequences of the wetness, and each has its own straightforward treatment.4
Dermatologist’s Take
Hyperhidrosis is one of the more satisfying things to treat, and one of the most under-treated. The average person who ends up in my office has had it since primary school, has never mentioned it to a doctor, and has quietly organized a decade of their life around it. There is nothing unusual about that, and it is worth naming, because the assumption that nothing can be done is the main obstacle.
The other thing worth saying is that the ladder is real, and skipping rungs rarely pays off. Antiperspirant used properly, then prescription strength, then a wipe or iontophoresis, then injections, then tablets. Surgery is last for a reason and I want people to understand compensatory sweating before they agree to it, not after.
— Dr. Schwarz, Board Certified Dermatologist
Myths
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- "Excessive sweating is just nerves." Anxiety makes any sweating worse, but in primary hyperhidrosis the wiring is set high to begin with. People with it sweat heavily in situations they find completely relaxing, and it commonly starts in childhood, long before anyone is anxious about it. Treating the sweating often reduces the anxiety, which tells you something about the direction of the relationship.
- "Antiperspirants cause breast cancer or Alzheimer's disease." These claims have been examined repeatedly and the evidence does not support them. Major cancer and health organizations have reviewed the underarm antiperspirant question and have not found a link.
- "Blocking sweat is unhealthy because it traps toxins." Sweat is mostly water and salt, with small amounts of other substances. Detoxification is done by the liver and kidneys, not the skin. Antiperspirants also only affect a small fraction of the body's sweat glands, and the body has no difficulty regulating its temperature without them.
- "Deodorant and antiperspirant are the same thing." They are not. Deodorant targets the bacteria that turn sweat into odor. Antiperspirant blocks the sweat duct so less sweat comes out. Many products contain both, but a product labeled only as a deodorant will not reduce sweating at all.
- "Botulinum toxin for sweating is a cosmetic treatment." It is an approved medical treatment for severe underarm hyperhidrosis, and insurance often covers it when antiperspirants have been tried and documented first. The rules vary by plan and country, so it is worth asking rather than assuming.
- "Surgery is the definitive cure." Cutting the sympathetic nerve does reliably stop palm sweating, but a large share of people then sweat more heavily on the trunk, back or legs instead. That compensatory sweating can be worse than the original problem and cannot be undone.
- "If you sweat this much, something must be seriously wrong with you." Primary hyperhidrosis is not a sign of underlying disease. What does deserve investigation is sweating that starts suddenly in adulthood, covers the whole body, happens during sleep, or comes with fever, weight loss or feeling unwell.
Your Routine
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Pick the tile that looks most like yours and we’ll show you a sample skincare routine.
And what is your skin like the rest of the time?
Dermatologist’s Take
The most common conversation I have about products is not about which antiperspirant to buy. It is about how to use the one already in the bathroom. Technique matters more than strength here, and getting it right is free.
The method, whichever product you use:
- Apply at night, before bed, not in the morning
- Skin must be completely dry. Towel dry, then wait, or use a hairdryer on cool for a few seconds
- A thin layer is enough. More product does not mean less sweat, it means more irritation
- Leave it on overnight and wash it off in the morning. It is already working in the duct by then
- Do not apply on a night you have shaved
- Use it nightly until sweating drops, usually one to two weeks, then cut back to once or twice a week
If it irritates - stinging, redness, flaking, or a darkening patch afterwards - do not abandon it.
- Skip two or three nights, then restart at a lower frequency
- Make sure the skin is bone dry before applying, since dampness is the usual culprit
- Moisturize in the morning after washing it off, not at night before applying
- Ask about buffered or lower-concentration prescription formulations, which exist for exactly this reason
If it is not doing enough, the next steps are prescription rather than shelf.
- A glycopyrronium wipe for the underarms
- An iontophoresis machine for hands and feet, which can be used at home
- Botulinum toxin injections, particularly for underarms
- Low-dose anticholinergic tablets, sometimes only on the days that matter
For feet, which get overlooked: the same antiperspirant works on soles, and the practical measures do real work. Rotate two pairs of shoes so each dries fully, use wool or wicking socks, change them midday, and treat athlete's foot promptly.
I would not spend money on detox products, sage supplements, or crystal and alum sticks marketed as natural antiperspirants. The last of these are deodorants, and they will not reduce how much you sweat.
If you are pregnant or breastfeeding, ask the doctor managing your pregnancy before starting prescription-strength antiperspirants, anticholinergic tablets or injections.
— Dr. Schwarz, Board Certified Dermatologist
Over-the-Counter Products
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Everything here you can buy without seeing anyone. Filter to one kind, or leave it to see them all.
No over-the-counter options match that type yet.
Prescriptions
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Pick the tile above that looks most like yours and this list narrows to what suits it. The basics stay put - a gentle cleanser, a moisturizer and a daily sunscreen are right whichever kind you have.
These need a prescription. Filter to one kind, or leave it to see them all.
No prescription treatments match that type yet.
Procedures
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These are done in the office, usually over several visits. Filter to one kind, or leave it to see them all.
No procedures match that type yet.
When to See a Doctor
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Two different reasons to go in, and it is worth separating them.
Get checked reasonably promptly if the sweating is new in adulthood, covers your whole body rather than a few areas, or wakes you soaked at night. The same applies if it comes with fever, unexplained weight loss, a racing heartbeat, shakiness, or feeling generally unwell. That combination points at a cause worth finding - an overactive thyroid, a medicine, a hormonal change, an infection, or occasionally something more serious - and a stronger antiperspirant is not the answer to any of them.
Book an ordinary appointment if focal sweating is affecting your daily life in any concrete way: ruined clothes, difficulty writing or using tools, avoiding handshakes, choosing what you wear around it, slipping in shoes, or repeated foot infections. Also book if two weeks of a clinical-strength antiperspirant used correctly at night has not helped, or if the products you have tried are irritating your skin too much to keep using.
The visit is worth it for practical reasons. It rules out a secondary cause with a short history and a couple of blood tests. It gets you prescription strength on the day. And it opens up the treatments that are not sold over the counter - wipes, iontophoresis, injections and tablets - which is where most of the benefit sits for anyone whose sweating is severe.
How It's Diagnosed
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Hyperhidrosis is diagnosed by history far more than by testing, and the questions are specific.
Doctors generally look for excessive sweating in a focal area lasting six months or more with no obvious cause, plus at least two of the following: it affects both sides roughly equally, it happens at least once a week, it stops during sleep, it started before the age of 25, there is a family history, and it interferes with daily activities. Meeting that pattern makes primary hyperhidrosis very likely, and no further testing may be needed.
Severity is usually recorded with a short four-point scale that asks how tolerable the sweating is and how much it interferes with life. It sounds like paperwork, but it is often what insurers require before covering injections, so it is worth answering carefully.
Ruling out a secondary cause is the other half of the visit. A medication review is the highest-yield step, since a long list of common drugs increases sweating. Blood tests for thyroid function and blood sugar are frequently done. Anything else is guided by what the history suggests rather than ordered routinely.
If a doctor needs to map exactly where sweat is coming from - usually before injections - they use the starch-iodine test. Iodine solution is painted on the skin, starch powder is dusted over it, and the areas that are sweating turn dark blue-black within a few minutes. It is simple, it is done in the room, and it reads the same on every skin tone. Research settings also weigh sweat collected on filter paper to measure the amount, but that is rarely part of ordinary care.
The main things being sorted out are primary versus secondary hyperhidrosis, and hyperhidrosis versus normal sweating that is being judged harshly. Both matter, and the answer changes the treatment.
Complications
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Hyperhidrosis — Complication
Hyperhidrosis — Complication
Lookalikes
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Hyperhidrosis — Lookalike
Hyperhidrosis — Lookalike
Hyperhidrosis — Lookalike
Questions Patients Ask
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Is hyperhidrosis dangerous?
The primary form is not dangerous in itself. Its costs are practical and social, plus a higher rate of skin problems from constant wetness - athlete's foot, rashes in skin folds, and softened, macerated skin. Sweating that is new, generalized, happens during sleep, or comes with weight loss or fever is a different matter and should be checked.
Why does my antiperspirant not work?
Most often because of when it is being used. Applied in the morning to damp skin, the active ingredient washes out of the sweat duct before it can settle. Applied at night to completely dry skin, the same product often works. If two weeks of that with a clinical-strength product has not helped, that is genuine failure and the reason to move up to prescription options.
How long do botulinum toxin injections last, and do they hurt?
They usually start working within a few days to a week and last several months before repeating. Underarm injections are well tolerated by most people. Palms and soles are more uncomfortable and are often done with numbing measures, and palm injections can cause temporary weakness in the hand.
Will treatment make me stop sweating everywhere?
No. Antiperspirants, wipes and injections act only where they are applied, and they affect a small share of the body's total sweat glands. Tablets work throughout the body, which is why they reduce heat tolerance and need care in hot weather or heavy exercise. The body has plenty of capacity to cool itself in every case.
Will it go away on its own?
Primary hyperhidrosis usually persists, though it often eases somewhat with age, particularly on the palms. It is best thought of as controlled rather than cured. Secondary hyperhidrosis frequently resolves once whatever is driving it is treated.
Should I have the surgery?
For most people, no. It reliably stops palm sweating, but a large share of people develop heavier sweating elsewhere afterwards, usually on the trunk, and that is permanent. It is reasonable to consider only for severe palm sweating after antiperspirants, iontophoresis, injections and tablets have all been genuinely tried.
References
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- Elrosasy A, Zeid MA, Samha R, et al. Efficacy and safety of topical glycopyrronium bromide in treating axillary hyperhidrosis: systematic review and meta-analysis. Scientific reports. 2024. — Scientific reports, 2024
- Sun J, Chen S, Yang T, et al. Efficacy and Safety of Botulinum Toxin Type A in Primary Axillary Hyperhidrosis: A Meta-analysis and Systematic Review. Aesthetic plastic surgery. 2025. — Aesthetic plastic surgery, 2025
- Hasimoto FN, Cataneo DC, Hasimoto EN, et al. Radiofrequency in the treatment of primary hyperhidrosis: systematic review and meta-analysis. Clinical autonomic research : official journal of the Clinical Autonomic Research Society. 2020. — Clinical autonomic research : official journal of the Clinical Autonomic Research Society, 2020
- Zhang W, Wei Y, Jiang H, et al. T3 versus T4 thoracoscopic sympathectomy for palmar hyperhidrosis: a meta-analysis and systematic review. The Journal of surgical research. 2017. — The Journal of surgical research, 2017
- Lima SO, Santos RS, Moura AMM, et al. A systematic review and meta-analysis to evaluate the efficacy of lumbar sympathectomy for plantar hyperhidrosis. International journal of dermatology. 2019. — International journal of dermatology, 2019
- Jankovic J, Carruthers J, Naumann M, et al. Neutralizing Antibody Formation with OnabotulinumtoxinA (BOTOX®) Treatment from Global Registration Studies across Multiple Indications: A Meta-Analysis. Toxins. 2023. — Toxins, 2023