Participants in this study will be people who have a history of delayed allergic reactions to penicillin, meaning their symptoms appeared more than six hours after taking the medication, or people who are unsure about when their reaction occurred. All participants will first receive a single test dose of amoxicillin. Those who tolerate this first dose without problems will then be randomly assigned to receive either amoxicillin capsules or placebo capsules for five days. Neither the participants nor the doctors will know which treatment each person is receiving during the study.

The study will monitor participants for any allergic reactions that occur up to seven days after the first test dose, with additional monitoring continuing up to fourteen days. Participants will have follow-up appointments either through telehealth or in person at the clinic. An independent panel of experts who do not know which treatment participants received will review any reactions to determine if they are truly immune-mediated allergic reactions. The study will also measure how the testing affects participants’ quality of life using a questionnaire at the beginning of the study and again at ninety days.

The purpose of the study is to find out the concentration of the Lepidoglyphus destructor extract that causes a skin reaction similar in size to the reaction caused by the histamine solution. Participants will undergo skin prick testing, where these solutions are applied to the skin to observe any allergic reactions. The study will help in understanding how potent the Lepidoglyphus destructor extract is in causing an allergic reaction compared to the standard histamine solution.

Participants in the study will have a history of inhalant allergies, such as rhinitis or asthma, specifically to Lepidoglyphus destructor. The study will involve a simple procedure where small drops of the solutions are placed on the skin, and the size of any resulting wheal, or raised bump, is measured. This will help in assessing the allergenic potency of the Lepidoglyphus destructor extract in comparison to the known effects of histamine.

Participants in the study will undergo a skin-prick test, which involves applying small amounts of the allergen extracts to the skin to see if a reaction occurs. This test will also include a positive control using histamine hydrochloride and a negative control using sodium chloride, which is a simple salt solution. The size of the skin reaction, or papule, will be measured to assess the response to the allergen extracts.

The study aims to better understand the skin reactions caused by these specific tree pollen allergens in individuals with a history of inhalant allergies, such as rhinitis, rhinoconjunctivitis, or asthma, related to Quercus ilex and Quercus robur. This research could help improve allergy testing and treatment for people sensitive to these tree pollens.

The purpose of the study is to determine the concentration of each pollen extract that causes a skin reaction similar in size to the reaction caused by the histamine solution. Histamine is a substance that naturally occurs in the body and is known to cause a reaction when applied to the skin, which helps in comparing the reactions to the pollen extracts. Participants will undergo the prick test with different concentrations of the pollen extracts, as well as the positive and negative controls, to measure the size of the skin reaction, known as a wheal.

The study will monitor the reactions at the test site on the skin and any other reactions that might occur. It will also track any side effects or adverse events that participants might experience during the study. The trial aims to provide valuable information about the sensitivity of individuals to these specific pollen allergens, which can help in understanding and managing allergies more effectively.