What is gravimetric sweat measurement?

A preweighed filter paper or gauze is placed on the dry skin for a fixed time (typically 5 minutes), then reweighed on an analytical balance. The weight gain is the amount of sweat, usually expressed as mg per 5 min or mg per min.

How much sweat is 'hyperhidrosis' by weight?

There is no universally accepted single cut-off. Clinical trials commonly enroll patients producing at least 50 mg of axillary sweat over 5 minutes. A 2015 review proposed 100 mg / 5 min as a physiological cut-off, since about 90% of healthy controls fell below that value in axillary and palmar sites.

What is a sudorometer?

A device that measures sweat rate in real time by sealing a small capsule to the skin, passing dry gas through it, and reading the humidity change downstream. Output is typically nanoliters or microliters per minute.

What is QSART used for?

The Quantitative Sudomotor Axon Reflex Test evaluates the postganglionic sympathetic sudomotor axon by stimulating a small area of skin with iontophoresed acetylcholine and recording the sweat response. It is used mainly in autonomic neurology (small-fiber neuropathy, autonomic failure), not to diagnose focal hyperhidrosis.

Is gravimetry done at every hyperhidrosis appointment?

No. It is used in research and in specialty centers to document response to treatment. Most routine clinical care relies on symptom history and the HDSS.

Why do different studies use different cutoffs?

There is no single validated threshold, and normal and hyperhidrotic ranges overlap. Cut-offs (50 mg/5 min, 100 mg/5 min, 20 mg/min, 10 mg/min) are pragmatic choices made by trial protocols and guideline groups, not diagnostic verdicts.

Research

How Doctors Measure Sweat: Gravimetry and Sudorometry

When researchers want to quantify sweat, they use one of two families of tools. Gravimetry weighs a preweighed filter paper or gauze before and after it sits on the skin for a fixed time, giving milligrams of sweat per unit time. Sudorometry (including the ventilated-capsule evaporimeter and the Quantitative Sudomotor Axon Reflex Test, QSART) measures the rate of sweating in real time by tracking humidity change over the skin. This page explains how each method works, the thresholds used in the research literature (for example, the 50 mg / 5 min axillary sweat criterion in botulinum-toxin trials), and what each method can and cannot tell a clinician. It is educational information, not medical advice.

By the Sweat Explained Editorial Team · Published 2026-07-19 · Last reviewed 2026-07-19 · Educational information, not medical advice.

Key statistics at a glance

50 mg / 5 min
gravimetric axillary threshold used to enroll patients in modern hyperhidrosis drug trials
Naumann/Allergan pivotal trials; FDA-registered studies
100 mg / 5 min
proposed cut-off distinguishing axillary hyperhidrosis from normal, based on ~90% of healthy controls falling below this level
Wolosker/Hund 2015 review
>20 mg/min (men), >10 mg/min (women)
axillary rates used as a diagnostic cut-off in clinical trials per IHhS guidance
International Hyperhidrosis Society
nanoliters/min
resolution of ventilated-capsule sudorometers (QSART, Q-Sweat) for autonomic testing
Illigens 2008; Novak 2011

Why measure sweat at all?

Most clinical decisions about hyperhidrosis rely on how bothered a patient is, captured by the HDSS. But research needs a number that does not depend on how a person feels that morning: something that can be compared between groups, before and after treatment, or across body sites. Objective sweat measurement fills that gap.

There is no single universally accepted cutoff for diagnosing hyperhidrosis by weight or rate alone. Reference intervals overlap between people who consider themselves normal and people diagnosed with hyperhidrosis, so measurement is used in combination with symptoms and impact rather than as a standalone test. Practical clinical care rarely requires gravimetry; it is largely a research tool.

Gravimetry: weigh the paper

Gravimetry is the workhorse of hyperhidrosis trials. The procedure, standardized in the pivotal onabotulinumtoxinA studies, is: the patient rests for about 30 minutes to acclimate, the axilla is dried, a preweighed filter paper or gauze is applied for exactly 5 minutes with the arm at the side, then it is weighed again on an analytical balance. The difference is expressed as milligrams of sweat per 5 minutes (or per minute).

In modern axillary hyperhidrosis trials, the standard entry criterion is production of at least 50 mg of sweat per axilla over 5 minutes at rest and room temperature. That threshold was chosen empirically from what self-identified "normal sweaters" produced in early volunteer studies. Later work suggested a higher cut-off may better distinguish disease from normal physiology: in Wolosker's review of gravimetric data, about 90% of healthy controls had axillary and palmar sweat production below 100 mg / 5 min, and average sweat production in hyperhidrosis studies exceeded 100 mg / 5 min in nearly every cohort. The International Hyperhidrosis Society guidance summarizes clinical-trial axillary cut-offs of >20 mg/min in men and >10 mg/min in women (means in normals were 14.4 and 9.4 mg/min respectively).

Gravimetric thresholds used in the literature

Different research protocols use different cutoffs. This is the source of much confusion when patients look up "how much is too much".

Selected gravimetric criteria for axillary and palmar hyperhidrosis
Site	Threshold	Context	Source
Axilla (each)	≥ 50 mg / 5 min	Standard entry criterion in FDA-registered onabotulinumtoxinA and topical anticholinergic trials	Naumann 2001; NCT02530294
Axilla	≥ 100 mg / 5 min	Proposed physiological cut-off (≈90% of controls fell below this)	Wolosker 2015 review
Axilla, men	> 20 mg/min (normal mean 14.4)	Clinical-trial cut-off summarized in IHhS diagnostic guidance	IHhS diagnosis guidelines
Axilla, women	> 10 mg/min (normal mean 9.4)	Clinical-trial cut-off summarized in IHhS diagnostic guidance	IHhS diagnosis guidelines
Palm	> 30–40 mg/min	Clinical-trial cut-off summarized in IHhS diagnostic guidance	IHhS diagnosis guidelines

These are research thresholds; they overlap with normal ranges and are not standalone diagnostic tests. Numeric values are as reported in each cited source.

Sudorometry: measure the rate directly

Sudorometers measure sweating by tracking how much water vapor leaves the skin, not by weighing the sweat itself. A ventilated capsule is sealed against the skin and a dry gas (typically nitrogen or dried room air) is passed through it; a hygrometer downstream reads humidity change, which is converted to sweat rate. This yields real-time output in nanoliters or microliters per minute.

The most common clinical sudorometer is the Quantitative Sudomotor Axon Reflex Test (QSART), developed by Low and colleagues in 1983. In QSART, acetylcholine is iontophoresed into the skin, and the resulting axon-reflex sweat response is recorded from four sites (forearm, proximal leg, distal leg, and foot over extensor digitorum brevis). It is used to assess postganglionic sympathetic sudomotor function in autonomic disorders and small-fiber neuropathy, not primarily to diagnose focal hyperhidrosis. Commercial systems (Q-Sweat) automate the capsule and flow control; because different devices produce different absolute values, laboratories use device-specific normative data.

Other sweat-measurement methods you may see cited

Gravimetry and QSART dominate, but the literature also describes:

Thermoregulatory sweat test (TST): the patient is warmed in a controlled chamber and sprayed with an indicator (alizarin red or iodine-starch mix) that changes color where sweat appears. This maps distribution and is used with QSART to localize lesions to pre- or postganglionic.
Silicone impressions: a silicone material is applied to the skin and captures the pattern of active sweat droplets, which are then counted under magnification. Useful in small-fiber neuropathy research.
Sympathetic skin response (SSR): an EMG-based measure of electrodermal activity, not of sweat volume itself; used in autonomic testing.
Qualitative starch-iodine (Minor's) test: maps where sweating occurs but does not quantify it; used to guide botulinum-toxin injection points.

What sweat measurement cannot do

Every method has a ceiling. Gravimetry gives a total over a fixed window but cannot separate a brief spike from steady sweating and depends on room temperature, hydration, activity, and acclimatization. Sudorometry gives rate over time but is sensitive to capsule leak, ambient humidity, and technique. Neither method has a clean cut-off that separates hyperhidrosis from normal sweating in every person, which is why the primary hyperhidrosis criteria (Hornberger 2004) rely on symptom features and impact rather than a required numeric threshold. Objective measurement is best understood as a research and monitoring tool, not a bedside diagnostic verdict.

Methodology and limitations

Numeric thresholds and procedural details were traced to primary sources: the pivotal onabotulinumtoxinA and topical anticholinergic trial protocols (which specify a 50 mg / 5 min axillary cut-off), the Wolosker 2015 gravimetric review (100 mg / 5 min proposed cut-off; approximately 90% of controls below), the International Hyperhidrosis Society diagnostic guidelines (site-specific rate cut-offs and normal means), the QSART methodology papers of Low et al. and the practical descriptions in Illigens & Gibbons 2008 and Novak 2011. Item counts and technique details (5-minute collection, 30-minute acclimatization, forearm vs thigh site preference) come from the cited protocols and reviews.

Limitations: measurement values differ meaningfully across devices, definitions, and populations. The 50 mg / 5 min threshold is a trial enrollment convention rather than a validated diagnostic cut-off. QSART is optimized for autonomic assessment, not hyperhidrosis severity. This page describes how the research tools work; it does not tell any individual whether they have hyperhidrosis. Anyone concerned about their sweating should discuss it with a clinician.

Frequently asked questions

What is gravimetric sweat measurement?: A preweighed filter paper or gauze is placed on the dry skin for a fixed time (typically 5 minutes), then reweighed on an analytical balance. The weight gain is the amount of sweat, usually expressed as mg per 5 min or mg per min.
How much sweat is 'hyperhidrosis' by weight?: There is no universally accepted single cut-off. Clinical trials commonly enroll patients producing at least 50 mg of axillary sweat over 5 minutes. A 2015 review proposed 100 mg / 5 min as a physiological cut-off, since about 90% of healthy controls fell below that value in axillary and palmar sites.
What is a sudorometer?: A device that measures sweat rate in real time by sealing a small capsule to the skin, passing dry gas through it, and reading the humidity change downstream. Output is typically nanoliters or microliters per minute.
What is QSART used for?: The Quantitative Sudomotor Axon Reflex Test evaluates the postganglionic sympathetic sudomotor axon by stimulating a small area of skin with iontophoresed acetylcholine and recording the sweat response. It is used mainly in autonomic neurology (small-fiber neuropathy, autonomic failure), not to diagnose focal hyperhidrosis.
Is gravimetry done at every hyperhidrosis appointment?: No. It is used in research and in specialty centers to document response to treatment. Most routine clinical care relies on symptom history and the HDSS.
Why do different studies use different cutoffs?: There is no single validated threshold, and normal and hyperhidrotic ranges overlap. Cut-offs (50 mg/5 min, 100 mg/5 min, 20 mg/min, 10 mg/min) are pragmatic choices made by trial protocols and guideline groups, not diagnostic verdicts.

Sources

Primary peer-reviewed studies and official sources first, then reviews and institutional framing (secondary).

Hund M, Kinkelin I, Naumann M, Hamm H. Definition of axillary hyperhidrosis by gravimetric assessment. Arch Dermatol. 2002;138(4):539-541. PubMed
Naumann M, Lowe NJ. Botulinum toxin type A in treatment of bilateral primary axillary hyperhidrosis: randomised, parallel group, double blind, placebo controlled trial. BMJ. 2001;323(7313):596-599 (defines the 50 mg / 5 min inclusion criterion). PubMed
Wolosker N, Krutman M, Kauffman P, et al. Distinguishing hyperhidrosis and normal physiological sweat production: new data and review of hyperhidrosis data for 1980-2013. Int J Dermatol. 2015;54(11):1319-1324. Full text
Low PA, Caskey PE, Tuck RR, Fealey RD, Dyck PJB. Quantitative sudomotor axon reflex test in normal and neuropathic subjects. Ann Neurol. 1983;14(5):573-580. PubMed
Illigens BMW, Gibbons CH. Sweat testing to evaluate autonomic function. Clin Auton Res. 2009;19(2):79-87. (secondary) PubMed
Novak P. Quantitative autonomic testing. J Vis Exp. 2011;(53):2502 (QSART/Q-Sweat methodology). (secondary) Full text
International Hyperhidrosis Society. Diagnosis guidelines: gravimetric measurement and clinical-trial cut-offs. IHhS clinician resource. (secondary) IHhS
Hornberger J, Grimes K, Naumann M, et al. Recognition, diagnosis, and treatment of primary focal hyperhidrosis. J Am Acad Dermatol. 2004;51(2):274-286. (secondary) Full text

How to cite this page

Sweat Explained. How Doctors Measure Sweat: Gravimetry and Sudorometry. Published 2026-07-19; last reviewed 2026-07-19. Available at: https://sweatexplained.com/research/measuring-sweat-gravimetry

Please cite the original studies for the underlying figures. Journalists are welcome to link to this page; the charts are original renderings of the cited data.