# Photoallergic reaction to sunlight - 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, Gillespie E. Photosensitivity and Photodermatoses. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026 Jan-. Updated 2026 Jan 31. Bookshelf ID: NBK431072; PMID: 28613726. - 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 PHOTOALLERGIC REACTION TO SUNLIGHT 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, Gillespie E. Photosensitivity and Photodermatoses. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026 Jan-. Updated 2026 Jan 31. Bookshelf ID: NBK431072; PMID: 28613726. 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 (8) - Ask how soon the rash follows light, whether it repeats, whether it swings with the seasons, and how long it lingers once exposure stops [rash] - Onset within minutes points to solar urticaria; a delay of hours to days fits photoallergy or polymorphic light eruption [rash · urticaria] - A constant rash with little seasonal swing suggests skin lupus or chronic actinic dermatitis instead [rash] - Take the whole drug and exposure history: prescriptions, off-the-shelf medicines, herbals, creams, perfumes, plants and workplace chemicals - Thiazide water tablets and doxycycline are the drugs most often behind it - Joint pains, mouth ulcers, cold blanching fingers or fatigue suggest connective tissue disease behind the rash [fatigue · mouth ulcers · rash] - Belly pain, nerve symptoms or dark urine point instead to acute porphyria [abdominal pain] - In a child, poor growth, neurological problems or cancers appearing young point to an inherited photosensitivity syndrome [failure to thrive] SIGNS - what you find (9) - The rash takes the sun-exposed sites: backs of the hands and forearms, the V of the chest, neck and face, while covered skin is spared [rash] - Sharp cut-off lines at collars, watch straps, jewellery or the hairline confirm a light-driven pattern - Sparing of skin that is exposed every day, such as the face, is a clue to polymorphic light eruption and reflects hardening [rash] - Eczema-like plaques favour photoallergy or chronic actinic dermatitis; weals favour solar urticaria [plaques · urticaria] - Bumps, plaques, small blisters and itchy nodules are the usual look of the idiopathic photodermatoses [blisters · itching · plaques · vesicles] - Ring-shaped plaques that flare in the sun suggest subacute cutaneous lupus [plaques] - Blisters, fragile skin and scarring on sun-exposed sites raise porphyria, above all porphyria cutanea tarda [blisters · scarring] - Look past the skin: scalp, nails, mucous membranes and for signs of systemic illness - Abnormal nailfold capillaries support dermatomyositis; mottled poikiloderma with sun damage suggests long-standing photosensitivity or an inherited syndrome TESTS (10) - Work in steps: history and examination first, then targeted bloods, light testing or biopsy only where they are indicated - Phototesting is a specialist tool in a few centres only; it pins down the wavelengths at fault and can reproduce the rash - Minimal erythema dose testing picks up abnormal sensitivity to UVA or UVB and separates a true photodermatosis from normal skin - Repeated UVA or UVB exposures across several days can reproduce chronic actinic dermatitis or polymorphic light eruption, though a false negative is common - Photopatch testing is the test when photoallergic contact dermatitis is suspected, run alongside ordinary patch testing to catch allergens that need light to act - Guidelines put photopatch testing on eczema-like sun-pattern rashes where the exposure history fits - ANA and extractable nuclear antigen panels only when connective tissue disease is suspected, never as routine screening - Blistering or painful sun sensitivity needs porphyrin studies on blood, urine and stool - Skin biopsy with immunofluorescence helps when the pictures overlap, but the findings are often non-specific and need reading in context - Suspected inherited photosensitivity needs specialist-centre work: post-UV cell survival, DNA repair studies or gene sequencing IF NOT THIS - what else fits (8) - Idiopathic photodermatoses, chiefly polymorphic light eruption and actinic prurigo - Skin lupus: think of it in a persistent sun-pattern rash, backed by systemic features, abnormal serology and typical biopsy - Dermatomyositis: sun sensitivity together with weak shoulder and hip muscles, or Gottron papules - Drug-induced photosensitivity: a recent medicine change plus a sharply sun-limited rash - Porphyria: blistering, fragile skin and scarring where the sun reaches - Metabolic causes, including the porphyrias and pellagra - Inherited photosensitivity syndromes: begin in early life, involve several organ systems, and carry high cancer risk - Toxic epidermal necrolysis or Stevens-Johnson syndrome falling in a sun-exposed pattern Source StatPearls "Photosensitivity and Photodermatoses" - 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). - While symptoms persist; review at 4-6 weeks Peds 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 an allergic/photoallergic skin reaction; dosing does not change with the trigger for the itch. Caution Widespread blistering or systemic symptoms suggesting a severe photosensitivity reaction, or an underlying photosensitising drug that must be stopped. 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. Does not replace photoprotection or stopping a photosensitising drug if one is implicated. 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)