Mast Cell Treatment in Post-tick Bite Illness (PTBI)
United States50 participantsStarted 2026-04-30
Plain-language summary
This is a Phase II double-blinded study to assess the safety, tolerability, and feasibility of the mast cell stabilizing medications ketotifen and cromolyn compared to participants receiving standard of care treatment with fexofenadine alone in participants who have persistent symptoms of mast cell activation following a documented tick-borne illness (Ehrlichiosis, Rocky Mountain Spotted Fever, Alpha-gal Syndrome).
Who can participate
Age range
21 Years – 65 Years
Sex
ALL
See this in plain English?
AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.
Inclusion Criteria:
* In order to be eligible to participate in this study, an individual must meet all of the following criteria:
* Ability to understand and provide informed consent in English (a translator will not be present during screening, consent or follow-up visits)
* Age 21-65 years old and of any gender, race, and ethnicity at the time of the initial visit.
* History of Ehrlichiosis and/or Rocky Mountain Spotted Fever (RMSF) within the last 36 months diagnosed and treated by a healthcare provider more than 6 months previously with current symptoms causing clinically significant distress or impairment in functioning as measured by a mast cell symptom scale score \>88 ± 9
* OR - History of alpha-gal syndrome (AGS) with an alpha-gal Immunoglobulin E (IgE) \>0.1 IU/mL and managed on an appropriate avoidance diet for more than 6 months previously with current symptoms causing clinically significant distress or impairment in functioning as measured by a mast cell symptom scale score \>88 ± 9
* Females of childbearing potential must have a negative pregnancy test prior to study entry
* Ability to refrain from diphenhydramine ("Benadryl") during the study period
Exclusion Criteria:
* Any individual who meets one or more of the following criteria will be excluded from participation:
* History of allergy, intolerance or hypersensitivity to fexofenadine, cromolyn or ketotifen (as documented by self-report and/or medical chart review)
* History of a prior c…
Questions worth asking your doctor
Bring these to your next appointment. They're a starting point for a shared conversation — not a sign you qualify or a recommendation to enrol.
1Based on my diagnosis and history, is this trial worth exploring for me — or is there a standard treatment we should try first?
2What does this trial's phase tell us about how much is already known about its safety and benefit?
3What would taking part actually involve for me — visits, tests, time, and travel?
4What are the known and possible risks or side effects I should weigh, and how would they be monitored?
5If this trial isn't the right fit, what other options or trials would you suggest I look into?
Generated to help you prepare — always confirm anything about your own eligibility and care with the study team and your doctor.
Questions for the trial coordinator
The trial coordinator is the person who runs the study day to day. These cover the practical side — logistics, costs, and what taking part would actually mean for your life. The study team confirms whether you meet the criteria; these are questions to ask, not a sign you qualify.
1What does taking part actually involve week to week — how many visits, where, and how long does each one take?
2What costs are covered by the study, and what might I have to pay for myself, including travel, parking, or time off work?
3What happens during screening, and what happens if the study team confirms I don't meet the criteria after those tests?
4Who pays for the scans, blood work, and other tests the trial requires — the study, my insurance, or me?
5How will being in the trial affect my regular care, and will my own doctor stay informed and involved?
6Can I leave the trial at any point if I change my mind, and what would happen to my care if I do?
A starting point for the conversation — always confirm anything about your own eligibility, costs, and care with the study team and your doctor.
What they're measuring
1
Change in Mast Cell Activation Symptom Score
Timeframe: Baseline, after 4 months of intervention