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Effect of Continuous Direct Current on Sweating and Quality of Life in Women with Primary Palmar Hyperhidrosis: A Randomized Controlled Trial

This double-blind randomized controlled trial demonstrates that continuous direct current (galvanic current) is an effective, noninvasive treatment for reducing sweating and improving quality of life in women with primary palmar hyperhidrosis compared to a sham intervention.

Original authors: Thaís Pedrosa Aragão, Gisela Rocha Siqueira, Maria das Graças Paiva, Rúbia Rayanne Souto Braz, Maria das Graças Rodrigues de Araújo, Marcelo Renato Guerino

Published 2026-07-14

📖 4 min read☕ Coffee break read

CC BY 4.0

Original authors: Thaís Pedrosa Aragão, Gisela Rocha Siqueira, Maria das Graças Paiva, Rúbia Rayanne Souto Braz, Maria das Graças Rodrigues de Araújo, Marcelo Renato Guerino

Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). ✨ This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer

Imagine your hands are like tiny, over-enthusiastic sprinklers that turn on whenever you get a little nervous, excited, or even just thinking about a test. For some people, these sprinklers go off way too hard, making palms so wet they can't hold a pencil or shake a hand without feeling awkward. This condition is called primary palmar hyperhidrosis.

A team of researchers in Brazil decided to see if they could turn down the water pressure on these sprinklers using a specific kind of electricity. They didn't use the scary, high-voltage kind, but a gentle, steady stream called continuous direct current (also known as galvanic current).

The Great Hand-Soak Experiment

The scientists gathered 60 women who had this "sweaty hand" problem. They split them into two teams for a secret game:

The Real Deal Team: These volunteers got the actual galvanic current treatment. They dipped their hands in a tub of water with electrodes, and a steady, mild electric current (between 20 and 35 mA) flowed through their palms.
The "Fake It" Team: These volunteers got a "sham" treatment. They felt a tiny, barely noticeable tingle (like a faint tickle) that felt like the real thing but wasn't strong enough to actually change anything.

Both teams went through 10 sessions, twice a week, with each session lasting 30 minutes. To see if it worked, the researchers used a cool "magic trick" called the starch-iodine test. They painted the hands with iodine and let starch dry on top. Wherever sweat appeared, the skin turned a deep, dark purple. It was like a heat map for moisture!

The Big Reveal

Here is what happened when the sprinklers were tested:

The "Fake It" Team: They didn't see much change. In fact, one person in this group actually got worse, and two others stayed exactly the same. Their hands kept dripping, and their quality of life didn't really improve.
The Real Deal Team: This group was the star of the show. By the fourth session, they started noticing their hands drying out. By the end of the 10 sessions, the "magic map" showed far fewer dark purple spots. In fact, the treatment made it 2.5 times more likely for a woman to see her sweating symptoms improve compared to the fake group.

How Long Did the Magic Last?

The researchers also asked the volunteers to keep a diary for 30 days after the treatments stopped to see when the sweating would come back.

The women who got the real electric current enjoyed a much longer break from the sweat. Their symptoms took longer to return.
The women who got the fake treatment saw their symptoms bounce back much faster.

The study found that the real treatment didn't just stop the sweat; it made the women feel significantly better about their lives. They felt more confident in social situations and less embarrassed. The researchers calculated that for every two women treated with this method, one would see a major benefit.

What About the "Why"?

The paper doesn't know the exact secret recipe of how the electricity works, but the scientists have a good guess. They think the electric current might be like putting a temporary "traffic jam" in the tiny tubes (sweat ducts) that carry sweat to the skin. It might also mess with the chemical signals that tell the sweat glands to turn on, effectively telling them, "Hey, take a break!"

The Bottom Line

This study shows that using a gentle, steady electric current is a real, effective, and non-invasive way to help women with sweaty hands. It's not a permanent cure—the sprinklers might turn on again after about a month—but it offers a safe, cheap, and painless way to get a long, dry break.

The researchers were careful to say that while the results are great, they need to keep studying to see how it works for everyone over a longer time. But for now, it looks like a little bit of electricity can go a long way in turning off the sprinklers.

Technical Summary: Effect of Continuous Direct Current on Sweating and Quality of Life in Women with Primary Palmar Hyperhidrosis

Problem Statement

Primary hyperhidrosis is a condition characterized by excessive sweating that exceeds thermoregulatory needs, significantly impairing daily activities and causing psychological distress, social isolation, and low self-esteem. While various interventions exist—including anticholinergic medications, aluminum chloride solutions, botulinum toxin injections, and sympathectomy—each presents limitations such as side effects, pain, high costs, or the risk of compensatory hyperhidrosis. Although electric current therapy (iontophoresis) has shown promise in uncontrolled studies, there is a need for rigorous, double-blind randomized controlled trials to validate its efficacy, specifically regarding continuous direct current (galvanic current) compared to sham interventions in women with primary palmar hyperhidrosis.

Methodology

The study was a double-blind, randomized controlled trial (RCT) conducted at the Federal University of Pernambuco, Brazil.

Participants: 60 female volunteers aged 18–30 years with primary palmar hyperhidrosis who had not received prior treatment for the condition. Exclusion criteria included sensitivity to electric current, skin lesions, cardiac issues, pregnancy, diabetes, uncontrolled hypertension, or cancer.
Study Design: Participants were randomly allocated into two groups:
- Intervention Group (G2): Received galvanic current (continuous direct current) at an intensity of 20–35 mA, adjusted for tolerance.
- Sham Group (G1): Received transcutaneous electrical nerve stimulation (TENS) at a sensory level insufficient to produce therapeutic effects, designed to mimic the sensation of active treatment.
Protocol: Both groups underwent 10 treatment sessions (twice weekly, 30 minutes per session). The setup involved immersing the affected hand in a water container with an active electrode on the palm and a reference electrode on the ipsilateral scapula. Polarity was automatically reversed every 15 minutes to minimize skin irritation.
Outcome Measures:
- Sweating: Assessed via the starch–iodine test (quantifying sweat presence via color change), treatment diaries (self-reported symptom changes), and remission diaries (tracking symptom return over 30 days post-treatment).
- Quality of Life: Evaluated using a validated, adapted questionnaire.
- Statistical Analysis: An intention-to-treat (ITT) framework was used. Comparisons included Student's t-test or Mann–Whitney U tests for continuous variables, Chi-square or Fisher's exact tests for categorical data, and Kaplan–Meier survival curves with log-rank tests for time-to-recurrence.

Key Contributions and Results

The study provides empirical evidence supporting the efficacy of continuous direct current over sham stimulation in treating primary palmar hyperhidrosis.

Reduction in Sweating: The galvanic current group demonstrated significantly earlier cessation of sweating compared to the sham group ( $p < 0.001$ ). Symptom improvement in the intervention group was noted starting from the fourth session, whereas the sham group showed no improvement until after the sixth session.
Starch–Iodine Test Results: Photographic analysis of the starch–iodine test revealed a significant reduction in moisture in the galvanic group. In the sham group, one participant experienced worsening symptoms, and two showed no change. Conversely, all participants in the galvanic group showed improvement. Statistical analysis indicated that galvanic treatment increased the likelihood of symptom improvement by more than 2.5 times compared to the sham group.
Quality of Life (QoL): While baseline QoL scores differed slightly between groups ( $p=0.041$ ), post-intervention analysis showed a highly significant improvement in QoL for the galvanic group ( $p < 0.001$ ). The galvanic group reported better outcomes in social interaction and emotional well-being. In contrast, some volunteers in the sham group reported worsening symptoms in these areas after ten sessions.
Remission and Satisfaction: The galvanic group exhibited a significantly longer latency for symptom recurrence (remission) compared to the sham group ( $p < 0.001$ ). Regarding satisfaction, 57% of the galvanic group reported being "very satisfied," and 100% indicated they would undergo the treatment again. In the sham group, 53% reported no change, and 37.5% stated they would not repeat the therapy.
Number Needed to Treat (NNT): The study calculated an NNT of two, suggesting that for every two patients treated with galvanic current, one will achieve a clinically meaningful benefit.

Significance and Claims

The authors conclude that continuous direct current is an effective, non-invasive, and low-cost therapeutic strategy for reducing sweating and improving quality of life in women with primary palmar hyperhidrosis.

Clinical Utility: The intervention offers a feasible alternative to more invasive or expensive treatments like botulinum toxin or sympathectomy. It produces rapid results with a relatively short treatment duration (10 sessions over 5 weeks).
Mechanism: The authors suggest the physiological mechanism involves the modulation of eccrine gland activity, potentially through the induction of functional impairment in sweat ducts, increased keratin plug formation, and altered cholinergic transmission.
Limitations: The study acknowledges limitations, including the lack of objective humidity measurement equipment, participant dropouts, a relatively small sample size, and a short follow-up period (30 days). The authors caution that while the benefits are significant, they are temporary, requiring regular maintenance.
Future Directions: The paper calls for future studies with larger cohorts, longer follow-up periods, and more precise objective measures to confirm these findings and optimize treatment parameters.

The study positions continuous direct current as a valuable tool for physiotherapists, offering a safe, well-tolerated, and high-satisfaction treatment option that addresses both the physiological symptoms and the psychosocial burden of primary palmar hyperhidrosis.