Investigators will study the effects of topical doxycycline on cutaneous allergic early and late phase responses by determining allergen skin responses in each subject after a single application to allergen induced allergic swelling of 2% doxycycline in emollient.

This study is a cross-sectional survey to be completed in a single consecutive two day study visit.

To assess the effect of topical doxycycline 2% emollient cream or control emollient on immediate hypersensitivity allergy skin tests responses, pruritus, and associated late phase skin swelling.

Investigators will use generic Aquaphor, a skin protectant, as the control emollient. The active ingredient in this cream is Petrolatum 42%. Inactive ingredients include ceresin, lanolin alcohol, microcrystalline wax, mineral oil, phenoxyethanol.

Adults (ages 18-75 yrs) treated at the SUNY Downstate/UHB Allergy Faculty Practice with known respiratory (allergic rhinoconjunctivitis and/or asthma), and who have previously been evaluated and are allergen skin prick test (SPT) positive to common aeroallergens will, after five days of non-use of oral antihistamine therapy, undergo limited repeat SPT with the same documented positive allergens (up to 5 allergens per subject).

1. Allergen skin prick testing (Dermapik method) will be done on the volar surface of each forearm, with identical SPT allergens. The profile to be tested will be individualized, from 1-5- allergens, to be determined by previous skin test positive results. Volunteers for the study who have not been previously tested will also be eligible, provided they have a history of symptoms consistent with allergic rhinoconjunctivitis and/or asthma. These subjects will receive testing with a select panel of 5 mixed allergens - to include both perennial (cat, dust mite) and seasonal (tree, grass, ragweed).

   Each subject will also be tested with standardized negative and positive controls of saline and histamine. Two control sites, left and right mid upper back, will both be pricked with histamine and saline.

2. After 20 minutes, the initial baseline determination of mean diameter (average of widest and its orthogonal measurement) will be taken of both wheal and flare, as will itch scores for each arm and each back control site (VAS (0 to 100 mm line) and verbal rating scale ( 0 - none, 1 - mild, 2 - moderate, 4 - severe)).

3. The location (right versus left) of placement of medication (active) versus control will be determined by a random numbers list for both forearm and back evaluation test sites. The subject will be blinded as to identity of the cream applied at each site.

   Using a single blind approach, a thin film of either doxycycline 2% cream or control emollient will be placed on entire test surface of either arm for an additional 30 min then removed. Repeat skin and itch measurements will immediately be done.

4. After an additional 30 minutes after wiping off the cream repeat skin and itch measurements will be done.

5. Reapplication - Investigators will then apply repeat film of cream to allergen test surface sites only then send the subject home with instructions to not wash the sites off for 6 hrs.

6. Repeat measurements at 24 hours post initial removal of cream.

Inclusion Criteria:

• Adult (ages 18-75) outpatients with diagnosis of allergic rhino-conjunctivitis and/or asthma who have previously undergone epicutaneous skin prick testing with detection of at least one allergen positive, and who may or may not have had a serum IgE level done as part of their routine evaluation.

Exclusion Criteria:

• Subjects unable/unwilling to undergo cessation of oral antihistamines for five days prior to testing.
• Current use of oral steroids or other systemic immunosuppressants, including omalizumab (anti-IgE therapy) and anti-IL-5 therapy.
• Allergic asthmatics with current uncontrolled asthma.
• Pregnant women

No plan.