How long after hyaluronidase (hyalase) injection can dermal fillers be re-injected?

When to Reinject Dermal Fillers After Hyaluronidase

Dermal fillers can be safely reinjected 6 hours after hyaluronidase administration, as hyaluronidase loses its effect in the dermis and subcutaneous tissue within 3-6 hours after injection. 1

Understanding Hyaluronidase Activity Timeline

Hyaluronidase is commonly used to dissolve hyaluronic acid fillers when correction is needed due to overcorrection, misplacement, or complications. The duration of its activity is critical for determining when it's safe to reinject fillers:

• At 3 hours post-hyaluronidase: Filler material begins to become evident again when reinjected
• At 6 hours post-hyaluronidase: Reinjected filler materials can restore almost their original volume with no significant differences from positive controls 1

Clinical Considerations for Reinjection

Patient Assessment Before Reinjection

• Ensure complete resolution of the issue that required hyaluronidase (overcorrection, misplacement, vascular occlusion)
• Check for any signs of inflammation, infection, or allergic reaction
• Evaluate if the tissue has returned to its pre-filler state

Potential Complications to Monitor

• Allergic reactions to hyaluronidase can occur and may present as focal erythematous plaques at the injection site 2
• Foreign body granulomas can develop with all injectable dermal fillers, typically appearing after a latent period of several months 3

Special Considerations

Hyaluronidase Allergies

• Patients with known bee venom allergies should not receive hyaluronidase as there is a risk of cross-reactivity 4
• Consider skin testing if there is concern about potential allergic reactions to hyaluronidase

Technique for Reinjection

• Use proper injection techniques to minimize trauma
• Consider using cannulas for subdermal injections to reduce bruising and edema 5
• Avoid reinjecting into areas with signs of inflammation or infection

Common Pitfalls to Avoid

1. Reinjecting too soon (before 6 hours) may result in immediate degradation of the new filler
2. Failing to recognize allergic reactions to hyaluronidase
3. Not documenting the hyaluronidase use in the patient's medical record
4. Overlooking the need for patient education about the temporary nature of results and possible need for additional treatments

By waiting at least 6 hours after hyaluronidase administration before reinjecting hyaluronic acid fillers, practitioners can ensure optimal results while minimizing complications.