Can an allergy to eyelash extensions be intermittent and unilateral, affecting one eye more than the other?

Can Allergic Reactions to Eyelash Extensions Be Intermittent and Unilateral?

Yes, allergic reactions to eyelash extensions can present intermittently and unilaterally, though this pattern should raise concern for alternative diagnoses including contact dermatitis, irritant reactions from formaldehyde-containing glues, or more seriously, sebaceous cell carcinoma masquerading as chronic unilateral blepharitis.

Understanding the Allergic Pattern

Why Unilateral Presentation Occurs

• Contact allergen exposure is inherently asymmetric - the application technique, amount of glue used, and proximity to the ocular surface varies between eyes, creating differential allergen exposure that can manifest as unilateral symptoms 1

• Formaldehyde is the primary culprit - chemical analysis reveals that 75% of professional eyelash glues and 13.3% of consumer glues release formaldehyde despite not declaring it as an ingredient, and this exposure can be asymmetric based on application technique 2

• The reaction can affect both the conjunctiva and eyelids - eyelash extension complications include keratoconjunctivitis (64 patients in one series) and allergic blepharitis (42 patients), with some patients developing both conditions simultaneously 1

Why Symptoms Come and Go

• Intermittent exposure drives intermittent symptoms - when extensions are removed, allergen exposure ceases and symptoms resolve with appropriate treatment (eye drops and/or ointments), only to recur with reapplication 1

• Variable formaldehyde release - different glue batches and environmental conditions (humidity, temperature) affect formaldehyde off-gassing, creating fluctuating allergen concentrations even with the same product 2

• The natural course of allergic conjunctivitis includes exacerbations and remissions, particularly when allergen exposure is intermittent rather than continuous 3

Critical Red Flag: Rule Out Malignancy First

Any chronic, unilateral blepharitis that is unresponsive to standard therapy must be evaluated for sebaceous cell carcinoma, which can be vision-threatening and life-threatening 4

When to Suspect Something More Serious

• Marked asymmetry or persistent unilateral disease warrants immediate eyelid biopsy, particularly if accompanied by focal lash loss, loss of normal eyelid margin anatomy, nodular masses, or ulceration 4

• Resistance to standard therapy for 2-3 weeks requires ophthalmology referral to exclude malignancy 4

• Unifocal recurrent chalazia in the setting of unilateral symptoms mandates biopsy 4

Diagnostic Approach

Initial Evaluation

• Examine the eyelid margin for vascularization, hyperemia, abnormal deposits at the base of eyelashes, and scaling to differentiate allergic blepharitis from other causes 4

• Look for cylindrical dandruff at the lash base, which is pathognomonic for Demodex blepharitis - a common alternative diagnosis that can also present unilaterally 4

• Assess for infectious causes including molluscum contagiosum, herpes simplex virus, and varicella zoster, all of which typically present unilaterally with eyelid involvement 5

• Differentiate from infection by noting the absence of vesicles, umbilicated lesions, or purulent discharge 5

Confirming the Diagnosis

• History is paramount - specifically ask about the temporal relationship between eyelash extension application/removal and symptom onset 1, 6

• Common symptoms include itching (38% of users), lashes pulling out (36%), heavy eyelids (34%), red eyes (34%), grittiness/foreign body sensation (32%), tearing (24%), and burning sensation (24%) 6

• Conjunctival scrapings looking for eosinophils can confirm allergic etiology 7

Management Strategy

Immediate Steps

• Remove the allergen source - discontinue eyelash extensions immediately, as this is the most effective intervention 1, 7

• Apply cold compresses for immediate symptomatic relief 3

• Use refrigerated preservative-free artificial tears four times daily to dilute allergens and inflammatory mediators on the ocular surface 3

First-Line Pharmacological Treatment

• Dual-action agents are most effective - olopatadine, ketotifen, epinastine, or azelastine provide both immediate relief and ongoing protection through combined antihistamine and mast cell stabilizer effects 3

• Store drops in the refrigerator for additional cooling relief upon instillation 3

• Implement eyelid hygiene with gentle cleansing to remove residual glue and allergens from the eyelid margin 4

Escalation for Persistent Symptoms

• Add a brief 1-2 week course of loteprednol etabonate if symptoms persist beyond 48 hours on dual-action drops, but this requires baseline and periodic intraocular pressure measurement plus pupillary dilation to evaluate for glaucoma and cataract 3

• Never use topical corticosteroids for more than 1-2 weeks due to risks of elevated intraocular pressure, cataract formation, and secondary infections 3

Severe or Refractory Cases

• Consider topical cyclosporine 0.05% at least four times daily for severe cases unresponsive to the above treatments, particularly if there is progression to atopic keratoconjunctivitis 3

• Topical tacrolimus 0.03% ointment can be used for eyelid involvement in patients 2 years or older, though be aware this may increase susceptibility to herpes simplex keratitis 8, 3

Critical Pitfalls to Avoid

• Never dismiss unilateral presentation without proper malignancy evaluation - this is the most critical error that can have life-threatening consequences 4

• Avoid punctal plugs in allergic conjunctivitis, as they prevent flushing of allergens and inflammatory mediators from the ocular surface 3

• Avoid chronic vasoconstrictor use - over-the-counter antihistamine/vasoconstrictor combinations cause rebound vasodilation (conjunctivitis medicamentosa) with prolonged use beyond 10 days 3

• Avoid oral antihistamines as primary treatment - they may worsen dry eye syndrome and impair the tear film's protective barrier 3

• Do not use topical antibiotics - they provide no benefit for allergic disease, induce toxicity, and contribute to antibiotic resistance 3

Follow-Up Strategy

• Frequency of follow-up depends on disease severity and treatment response, with visits timed during symptomatic periods 3

• If corticosteroids are used, baseline and periodic intraocular pressure measurement and pupillary dilation must be performed throughout treatment 3

• Monitor for keratoconus in patients with atopic disease, as adequate allergy control and preventing eye rubbing can decrease ectasia progression 3

• Refer to ophthalmology if symptoms persist beyond 2-3 weeks despite conservative management or if there is any concern for unilateral disease unresponsive to initial therapy 4