Foul-Smelling Sweat (Bromhidrosis)
Critical First Step: Rule Out Secondary Causes
Before treating bromhidrosis as a primary condition, you must systematically exclude secondary causes through laboratory evaluation, as conditions like hyperthyroidism, diabetes, and cystic fibrosis are frequently missed and can present with malodorous sweat. 1, 2
Essential Laboratory Workup
- Obtain TSH and free T4 to screen for hyperthyroidism 1, 2
- Check hemoglobin A1c to assess for diabetes mellitus 1, 2
- Complete blood count and complete metabolic panel 1, 2
- Serum calcium levels, vitamin D, and iron studies 1
- In infants with foul-smelling sweat: sweat chloride testing is mandatory to exclude cystic fibrosis, particularly if accompanied by bulky, foul-smelling stools, poor weight gain, or recurrent respiratory infections 3
Focused History Elements
- Medication review: anticholinergics, dopamine-reuptake inhibitors, diuretics, oral retinoids, and antipsychotics can cause secondary hyperhidrosis 1
- Associated symptoms: palpitations, headaches, anxiety, weight changes, heat intolerance, recent fever or gastrointestinal illness 1
- Timing and distribution of sweating and odor 1
- Aggravating factors: poor hygiene, diabetes, intertrigo, erythrasma, obesity—all promote bacterial overgrowth that worsens bromhidrosis 4
Physical Examination Priorities
- Check for hypertension and tachycardia (pheochromocytoma) 1
- Thyroid examination for enlargement or nodules 1
- Signs of heart failure 1
- Neurological findings suggesting Parkinson's disease, stroke, or autonomic dysfunction 1
Understanding Bromhidrosis Pathophysiology
Bromhidrosis results from bacterial decomposition of apocrine or eccrine sweat, though histologic studies show that apocrine gland hyperactivity (numerous, enlarged glands with decapitated epithelial cells) contributes more significantly than bacterial breakdown alone 4, 5. The condition is further aggravated by underlying disorders promoting bacterial overgrowth 4.
Treatment Algorithm
First-Line: Conservative Measures
Start with topical antiperspirants, antibacterial agents, and fragrance, as bromhidrosis usually responds to these measures 6, 4.
- Antiperspirants/deodorants: Routine use is not contraindicated despite weak evidence suggesting they may worsen hyperhidrosis 2
- Antibacterial soaps or washes to reduce bacterial colonization 6, 4
- Loose, breathable cotton clothing for symptomatic relief 2
- Improved hygiene practices 4
Second-Line: Botulinum Toxin Therapy
For mild-to-moderate symptoms refractory to conservative measures, botulinum toxin therapy shows consistent benefit, though it requires repeated treatments 7.
- Botulinum toxin A reduces sweat production, thereby decreasing substrate for bacterial decomposition 6, 7
- Treatment intervals vary; expect need for ongoing maintenance 7
Third-Line: Laser or Microwave Therapy
For refractory cases, laser therapy should be considered over microwave therapy, as it is better studied with biopsy-proven results, though long-term effects remain unknown 7.
- Microwave-based therapy shows promising results but requires larger cohort studies specifically for bromhidrosis 7
- Both modalities target sweat gland destruction 7
Fourth-Line: Surgical Intervention
Surgery has the best long-term prognosis for severe, refractory bromhidrosis, as surgical removal of apocrine glands is the most satisfactory and logical treatment given the histologic basis of the condition 7, 5.
- Critical pitfall: Do NOT use incision and drainage for hyperhidrosis-related cysts or nodules—this has nearly 100% recurrence rates; deroofing is preferred if surgical intervention is needed 2
- The ideal surgical method remains unknown, requiring shared decision-making with the patient 7
Special Populations
Infants with Foul-Smelling Sweat
- Sweat chloride level ≥60 mmol/L confirms cystic fibrosis; values 30-59 mmol/L require extended CFTR genetic testing 3
- Red flags: persistent cough, bulky foul-smelling stools, poor weight gain, frequent respiratory infections, salty-tasting skin 3
- Refer to specialized CF center if suspected 3
Generalized Hyperhidrosis with Odor
- May require oral anticholinergic agents if secondary to systemic disease 6
- Specialist consultation indicated for abnormal thyroid function, suspected pheochromocytoma, or cardiovascular disease 1
Critical Pitfalls to Avoid
- Never assume primary bromhidrosis without completing the full secondary cause workup—treatable conditions like thyroid dysfunction, diabetes, medication-induced hyperhidrosis, and pheochromocytoma are frequently missed 1, 2
- Treat the underlying hyperhidrosis to control body odor, rather than just providing deodorant recommendations 2
- Do not skip specialist referral when red flags are present (thyroid abnormalities, diabetes, cardiovascular disease, neurological findings) 1