When are Unna boots contraindicated?

Contraindications to Unna Boot Use

Unna boots should not be used in patients with peripheral arterial disease (PAD), active infection requiring frequent wound inspection, or known allergies to boot components (particularly parabens or hexachlorophene). 1

Absolute Contraindications

Peripheral Arterial Disease

• Do not apply compression therapy, including Unna boots, when ankle-brachial index (ABI) <0.5 or ankle pressure <50 mmHg 1
• Compression may aggravate symptoms in patients with arterial inflow limitation and can worsen tissue ischemia 1
• Before applying any compression device, assess pedal pulses and perform vascular testing if claudication symptoms or decreased/absent pulses are present 1
• Patients with toe pressures <30 mmHg or TcPO2 <25 mmHg require revascularization consideration before compression therapy 1

Active Deep or Severe Infection

• Unna boots are contraindicated when deep (potentially limb-threatening) infection is present 1
• Moderate to severe infections require urgent surgical evaluation for debridement and abscess drainage, which necessitates frequent wound access 1
• The rigid, non-removable nature of Unna boots prevents the frequent wound inspection and local care required for infected ulcers 1

Known Allergic Reactions

• Allergic contact dermatitis to preservatives in Unna boots, particularly parabens and hexachlorophene, has been documented 2
• Patients with prior reactions to these components should not receive standard Unna boot formulations 2
• Preservative-free alternatives may be considered if allergy to specific components is identified 2

Relative Contraindications Requiring Caution

Heavily Exudating Wounds

• Ulcers with heavy exudate require frequent dressing changes that are incompatible with the weekly change schedule of Unna boots 1
• Consider removable compression devices when frequent local wound care is necessary 1

Mild Infection Under Treatment

• When mild infection is present but being actively treated, removable compression devices are preferred over Unna boots to allow wound monitoring 1
• Once infection is fully controlled, Unna boots may be reconsidered 1

Conditions Requiring Frequent Wound Assessment

• Diabetic foot ulcers in patients with neuropathy and loss of protective sensation require regular inspection to detect early signs of deterioration 1
• The inability to easily remove Unna boots for daily inspection makes them unsuitable for high-risk diabetic foot wounds 1

Clinical Decision Algorithm

Step 1: Assess vascular status

• Measure ABI and ankle pressures
• If ABI <0.5 or ankle pressure <50 mmHg → Do not use Unna boot 1
• If mild PAD present (ABI 0.5-0.8) → Consider alternative compression with close monitoring 1

Step 2: Evaluate for infection

• Assess wound depth and signs of infection
• If moderate/severe infection or deep tissue involvement → Do not use Unna boot 1
• If mild superficial infection → Use removable device until infection resolves 1

Step 3: Consider wound characteristics

• Heavy exudate requiring daily changes → Do not use Unna boot 1
• Stable wound with minimal exudate → Unna boot appropriate 3, 4

Step 4: Screen for allergies

• Ask about prior reactions to zinc oxide, parabens, or preservatives
• If positive history → Use preservative-free formulation or alternative compression 2

Common Pitfalls to Avoid

• Never apply Unna boots without first assessing arterial perfusion - this is the most critical error that can lead to tissue necrosis 1
• Do not use Unna boots as a substitute for addressing underlying ischemia; revascularization must be considered first in PAD patients 1
• Avoid using Unna boots in diabetic patients with high-risk feet who require daily wound inspection 1
• Do not continue Unna boot therapy if the patient develops new pain, as this may indicate worsening ischemia or infection 1