Antihistamines and COVID-19: March 2024 Lab Findings

A small set of common antihistamines blocked SARS-CoV-2 infection in lab-grown cells, offering a possible path for drug repurposing. Researchers tested hydroxyzine, diphenhydramine and azelastine and saw reduced viral entry under controlled conditions. These results came from cell tests, not human trials, so there is no proof these drugs work the same way in people. Still, the findings matter because these medicines are already approved, widely available and well studied for other uses.

What the lab tests showed

Scientists exposed cultured human cells to SARS-CoV-2 after treating them with each antihistamine. They measured virus entry and replication and reported lower infection markers when cells received hydroxyzine, diphenhydramine or azelastine. The study used doses that worked in the dish, but those doses might not be safe or effective in people.

What this means for you

Don’t start taking these drugs to prevent or treat COVID-19 without a doctor’s advice. Antihistamines have side effects like drowsiness, dry mouth and interactions with other medicines. If future clinical trials confirm benefit, doctors could consider repurposing them as early treatment options or as part of combination therapies. For now follow proven measures: vaccination, testing when exposed, wearing masks in crowded places and seeking medical care if symptoms worsen.

We covered this research in March 2024 because it points to quick wins from existing drugs and the need for careful clinical work. Stay tuned to NorthwestPharmacy.SU for updates on trial plans, safety notes and practical advice about medications. If you want specifics from the lab study, our full post summarizes methods, the cell lines used and the exact antihistamines tested. Questions? Ask your pharmacist or doctor and mention this March report so they can give targeted guidance.

Researchers typically move from cell work to animal models, then to small human trials that test safety, dose and early signs of benefit. Those trials check for side effects, whether the drug reaches the right tissues, and if it lowers viral load or speeds recovery. Because hydroxyzine and diphenhydramine are older drugs with known safety profiles, regulators may move faster, but only solid trial data will change treatment guidelines. Azelastine is often used as a nasal spray; its local effect makes it interesting for blocking a virus that enters through the nose. That said, nasal sprays can still cause side effects and must be studied for safety at antiviral doses.

Ask your healthcare provider before changing any allergy or cold medicine routine. Keep an up-to-date medication list, mention sleepiness or heart problems that some antihistamines can worsen, and never mix medicines without advice. We will watch for clinical trial news and report practical, evidence-based updates on NorthwestPharmacy.SU.

If you want the full technical breakdown, our March post lists the lab methods, cell types, exact concentrations used and the study authors so you can read the original report. Subscribe to our pharmacy newsletter for alerts and short summaries when trials start or safety updates appear. Follow your pharmacist for practical medication advice today.