# Idiopathic photodermatosis - Category: acute - Review status: reviewed (every claim checked against a document named on this page) - Sources: DailyMed SetID 8274ca80-e7d3-4f4f-9901-cc5c589b4fef sections 1 and 2.2, https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=8274ca80-e7d3-4f4f-9901-cc5c589b4fef · Levocetirizine dihydrochloride tablets US prescribing information, sections 1 and 2 Dosage and Administration (DailyMed SetID 8274ca80-e7d3-4f4f-9901-cc5c589b4fef) · Sathe NC, Ramsey ML. Polymorphic Light Eruption. [Updated 2026 Feb 15]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026 Jan-. Bookshelf ID: NBK430886. PMID: 28613636. - Verified date: 2026-08 ## Verified against - DailyMed SetID 8274ca80-e7d3-4f4f-9901-cc5c589b4fef sections 1 and 2.2, https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=8274ca80-e7d3-4f4f-9901-cc5c589b4fef ## Treatment metadata - Levocetirizine — 5 mg — oral.solid ## Complete treatment card ```text IDIOPATHIC PHOTODERMATOSIS Sources: DailyMed SetID 8274ca80-e7d3-4f4f-9901-cc5c589b4fef sections 1 and 2.2, https://dailymed.nl m.nih.gov/dailymed/drugInfo.cfm?setid=8274ca80-e7d3-4f4f-9901-cc5c589b4fef · Levocetirizine dihydrochloride tablets US prescribing information, sections 1 and 2 Dosage and Administration (DailyMed SetID 8274ca80-e7d3-4f4f-9901-cc5c589b4fef) · Sathe NC, Ramsey ML. Polymorphic Light Eruption. [Updated 2026 Feb 15]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026 Jan-. Bookshelf ID: NBK430886. PMID: 28613636. Review status: REVIEWED against the source listed above (2026-08) IS IT THIS? - reference only, to read alongside your own examination SYMPTOMS - what the patient reports (4) - It starts after the first real sun exposure of the year, typically outdoors in spring or early summer - A clear winter followed by an abrupt return once the sun comes back is highly characteristic - The gap between sunlight and rash is the key clue: lesions come up hours to days later [rash] - Fierce itching, burning or stinging, sometimes before anything can be seen [itching] SIGNS - what you find (4) - It picks the newly uncovered skin: neck and upper chest, outer forearms, backs of the hands, legs and feet - The face is usually spared, probably because it is exposed all year and has hardened to light - The rash differs from person to person but keeps the same form in one patient: papules, plaques, blisters, lichenoid lesions or itchy nodules [blisters · itching · papules · plaques · rash] - Lesions clear without scarring once sun is avoided, though repeated exposure drags it out until the skin hardens to light TESTS (7) - The diagnosis is clinical, made on the story and the examination - Laboratory work is not needed unless the picture is unusual or hints at systemic disease - Skin biopsy can exclude other sun-triggered rashes but its own findings are non-specific - Antinuclear antibodies can be positive at low titre, which does not mean lupus without clinical features - Test porphyrins if porphyria is a possibility; they come back normal in this condition - Photoprovocation can reproduce the rash but misses up to 40% and is a specialist-centre test - In one series of 94 patients, 14 later developed autoimmune disease, 2 of them lupus, and 13 developed thyroid disease, though the link is unproven IF NOT THIS - what else fits (4) - Cutaneous lupus is the one that matters most: longer-lasting lesions, the face often involved, positive direct immunofluorescence and abnormal serology - Solar urticaria comes up within minutes of sunlight and fades quickly once out of it, unlike the delayed rash here - Chronic actinic dermatitis: persistent eczema-like plaques with heavy light sensitivity and no seasonal hardening - Also consider atopic eczema made worse by sun, a drug causing photosensitivity, porphyria cutanea tarda and erythropoietic protoporphyria Source StatPearls "Polymorphic Light Eruption" - disease-level clinical article Status traced to the source above 1. LEVOCETIRIZINE [1st line] Adult 5 mg PO once daily in evening (2.5 mg once daily may suffice). Peds 6 to 11 years: 2.5 mg once daily in the evening (Age 6-11y: 2.5 mg (1/2 scored tablet) PO once daily in evening; age <6y: use oral solution.) Source DailyMed SetID 8274ca80-e7d3-4f4f-9901-cc5c589b4fef sections 1 and 2.2, https://dailymed .nlm.nih.gov/dailymed/drugInfo.cfm?setid=8274ca80-e7d3-4f4f-9901-cc5c589b4fef Why Standard second-generation antihistamine dose for the itch of polymorphic light eruption/idiopathic photodermatosis; dosing does not change with the trigger for the itch. Caution Rule out lupus erythematosus or porphyria as an underlying cause if the eruption is recurrent or atypical. Evening dosing suits itch that is often worse at night. Do not combine with cetirizine - levocetirizine is cetirizine's active component, so together they double the dose. Reduce to 2.5 mg in mild renal impairment. Treats itch only; if the eruption is recurrent or atypical, investigate for an underlying cause such as lupus erythematosus or porphyria rather than relying on the antihistamine. Contraindicated in end-stage renal disease (CLcr <10 mL/min) and hemodialysis. Egypt ZALKEVOR 5 MG 10 F.C.TABS. EL-OBOUR > RE... 5.50 EGP (0.55/unit) RHIPGIC 5 MG 30 F.C. TABS. P & C LABS 19.50 EGP (0.65/unit) LERGOPAN 5 MG 10 F.C.TABS. PHAROPHARMA 7.50 EGP (0.75/unit) LEVOCITRONE 5 MG 10 F.C.TABS. EGYPHAR 21.00 EGP (2.10/unit) RAMATRIZINE 5 MG 30 F.C.TABS. EGPI > RAMAPH... 96.00 EGP (3.20/unit) LEVOHISTAM 5 MG 30 F.C.TABS. EGPI > UTOPIA 117.00 EGP (3.90/unit) ARAXILEVE 5 MG 30 ORO-DISPERSIBLE TABS. JEDCO INT. CO. FOR PHARMACEUTICA... 51.00 EGP LEVCET 5MG 20 ORODISSOLVABLE TABS. MARCYRL PHARMACEUTICAL INDUSTRIES (MPI) 85.00 EGP MERVOZA 2.5MG/5ML SYRUP 120 ML GLOBAL NAPI P... 8.00 EGP -> ? strength differs, ? different route - not oral solid MODALLERGE 0.5MG/ML ORAL SOL. EGPI > MODERN... 8.00 EGP -> ? strength differs, ? different route - not oral solid Prices are indicative (dataset snapshot 2026-06); verify with the pharmacy. ``` --- Dawaa Reference is a reference for prescribers, not a medical device, and does not replace clinical judgement. [Privacy policy](/privacy)