What are the side effects of Cantharone Plus (cantharidin)?

Side Effects of Cantharone Plus (Cantharidin)

Cantharone Plus can cause significant blistering, pain, and potential skin irritation, with the most common side effects being painful blisters that develop within 24 hours after application. 1

Primary Side Effects

• Expected Effects (Therapeutic Action):

  • Blistering (occurs in ~57% of patients) 2
  • Acantholysis (detachment of desmosomes from tonofilaments) 3

• Common Adverse Effects:

  • Pain (7-85.7% of patients) 4
  • Significant blistering beyond treatment area (2.5%) 2
  • Discomfort developing 24 hours after painless application 1

• Less Common Adverse Effects (<1%):

  • Pruritus (itching) 2
  • Mild infection 2
  • Significant irritation 2
  • Id reactions (autoeczematization) 2
  • Bleeding 2
  • Hyper/hypopigmentation (1.8-53.3%) 4

Mechanism of Action and Application

Cantharone Plus contains cantharidin, which is a vesicant (blistering agent) that:

1. Triggers acantholysis (breakdown of connections between skin cells)
2. Has a superficial nature of injury that reduces scarring risk 1
3. Features painless application, with discomfort developing only when blistering occurs in the 24 hours following application 1

Special Considerations

Formulations

Cantharone Plus typically contains:

• Cantharidin (1%)
• Salicylic acid (30%)
• Podophyllotoxin (2%) 3

This combination is more potent than standard cantharidin (0.7%) preparations and is primarily indicated for plantar warts, while the standard preparation is used for common warts, periungual warts, and molluscum contagiosum 3.

Toxicity Warning

Cantharidin is highly toxic if taken systemically 1. Oral ingestion can cause:

• Ulceration of gastrointestinal and genitourinary tracts
• Electrolyte disturbances
• Renal function impairment 3

Safety Profile

Despite potential side effects, cantharidin has been shown to be relatively safe when properly applied by healthcare providers:

• In a retrospective review of 405 children treated for molluscum contagiosum, only 11% experienced adverse events 2
• No cases of systemic intoxication or scarring have been reported with proper physician use 5
• Parent satisfaction rates with cantharidin treatment are high (86%) 2

Application Precautions

To minimize adverse effects:

1. Avoid application near eyes, face, genitals, or mucous membranes
2. Do not apply to irritated or broken skin
3. Limit application to small surface areas
4. Follow physician instructions for washing off the medication (typically 2-6 hours after application)
5. Avoid covering treated areas with occlusive dressings unless specifically instructed

Regulatory Status

Cantharone Plus is not FDA-approved, which could be related to its potential toxic effects following oral ingestion 3. However, it remains a commonly used treatment option among dermatologists, particularly pediatric dermatologists 6.