Service: Fotona SP Dynamis (Er:YAG 2940 nm / Nd:YAG 1064 nm) & StarWalker MaQX (QS 1064/532 nm ± dye 585/650 nm).

Cause / Mechanism

Immediate or delayed cutaneous reactions after laser may reflect: mast‑cell degranulation (acute urticaria), phototoxic/photoallergic responses from photosensitising medicines or cosmetics, allergic contact dermatitis to preps/dressings, or non‑specific exaggerated erythema from parameter choice and recent UV exposure. ^{1 2 3}

Risk Factors

• Patient: history of atopy/urticaria, autoimmune thyroid disease, recent viral illness; Fitzpatrick I–III with high UV exposure.
• Medicines & topicals: photosensitisers (e.g., doxycycline, amiodarone, thiazides, retinoids, St John’s wort), fragrances/preservatives (MI/MCI), adhesives. ^{2 4 5}
• Procedure/environment: high fluence/short pulse, large treatment fields, occlusive dressings, recent tanning. ^{1 3}

Signs & Symptoms

• Urticaria: transient pruritic wheals (<24 h each), possible angioedema.
• Photosensitivity: exaggerated erythema, burning, edema confined to light‑exposed areas; photoallergy may eczematise.
• Allergic contact dermatitis: eczematous plaques at contact sites (prep solutions, adhesives, dressings).
• Red flags: airway/lip/tongue swelling, dyspnoea, hypotension → treat as anaphylaxis. ^{6 7}

Prevention

• Pre‑treatment screening: atopy/urticaria history; recent illnesses; medication review for photosensitisers. ^{2 4}
• Choose non‑sensitising skin preps; avoid fragrances/preservatives where possible; patch‑test dressings for highly sensitive patients. ⁸
• Parameter titration and test spots; enforce strict sun avoidance and SPF 50+. ^{1 9}

Management Protocol

Immediate Actions:

• Stop laser; assess ABCs.
• For generalised urticaria without red flags: give a non‑sedating oral antihistamine per guideline dosing (cetirizine/loratadine/fexofenadine). ⁶
• Cool compresses; avoid irritant topicals.
• For contact dermatitis/photoallergy: discontinue culprit; mild–moderate potency topical corticosteroid and emollients; short course only on face. ⁸

Anaphylaxis (if airway, breathing, circulation compromise):

• Administer intramuscular adrenaline (epinephrine) to mid‑outer thigh immediately; call ambulance; lay patient flat; oxygen if available; repeat at 5 minutes if no response. Follow clinic anaphylaxis protocol and national action plan. ⁷

Photosensitivity due to Medicines:

• Identify and document photosensitising agent; consider discussion with the prescribing clinician regarding cessation or timing around procedures. Strict photoprotection (SPF 50+, clothing, shade) and symptomatic care. ^{4 5 9}

Escalation / Referral:

• Persistent or recurrent urticaria >6 weeks → GP/allergy referral.
• Severe contact dermatitis or diagnostic uncertainty → dermatology (consider patch testing).
• Suspected severe photoallergy or systemic photosensitivity → dermatology/photobiology unit. ^{6 8}

Follow‑up & Documentation

• Record onset, distribution, suspected triggers (preps, dressings, meds), laser parameters and response to treatment; photograph where appropriate.
• Provide written aftercare and avoidance advice; arrange follow‑up within 24–72 h depending on severity.
• Update consent forms and pre‑procedure checklists if new allergy/trigger identified; include in quality review. ^{1 6}

Sources

1. AS/NZS 4173:2018 Safe use of lasers and intense light sources in health care — screening, test spots and parameter titration., viewed 7 October 2025, https://www.standards.org.au ↩︎
2. TGA / NPS MedicineWise. Drug‑induced photosensitivity — consumer and clinician resources., viewed 7 October 2025, https://www.nps.org.au/consumers/drug-induced-photosensitivity ↩︎
3. ARPANSA. Advice for providers: lasers and intense light sources for cosmetic purposes., viewed 7 October 2025, https://www.arpansa.gov.au ↩︎
4. TGA. Medicines safety communications — photosensitising medicines (e.g., doxycycline)., viewed 7 October 2025, https://www.tga.gov.au ↩︎
5. Australian Government Healthdirect. Photosensitivity and sun reactions — overview., viewed 7 October 2025, https://www.healthdirect.gov.au/sun-sensitivity-photosensitivity ↩︎
6. ASCIA (Australasian Society of Clinical Immunology and Allergy). Urticaria guidelines & patient information., viewed 7 October 2025, https://www.allergy.org.au/patients/skin-allergy/urticaria-hives ↩︎
7. ASCIA. Anaphylaxis clinical update and action plans (adrenaline dosing, positioning, repeat dosing)., viewed 7 October 2025, https://www.allergy.org.au/hp/papers/acute-management-of-anaphylaxis-guidelines ↩︎
8. Australasian College of Dermatologists. Contact dermatitis (patch testing, management)., viewed 7 October 2025, https://www.dermcoll.edu.au ↩︎
9. Cancer Council Australia. Sun protection recommendations (SPF 50+, shade, clothing)., viewed 7 October 2025, https://www.cancer.org.au ↩︎