Dr Shepherd on Treating Long Covid with Histamine Receptor Antagonists

June 9, 2021


Earlier this year I attended a medical webinar where we heard about the use of antihistamine drugs as a possible treatment for Long Covid.

Dr.Shepherd, MEA Hon Medical Adviser
Dr Charles Shepherd

The encouraging results from a small preliminary observational study have now been made available as a pre-print publication found here.

The beneficial use of two types of antihistamine drug – known as H1 and H2 histamine antagonists – could relate to the way in which some people with Long Covid have symptoms that are consistent with histamine release, possibly being triggered by the viral infection, and linked to T cell dysfunction, which is a key part of the immune system response to viral infections

These findings could also link in to a condition called mast cell activation syndrome (MACAS) – where mast cell disruption is the source of histamine.

“From the point of view of ME/CFS, these findings are interesting because T cell dysfunction is a research finding in ME/CFS and there are indications that MCAS is more common in ME/CFS.

“It also illustrates how research into both the cause and management of Long Covid could produce useful findings that are relevant to ME/CFS.”

Dr Charles Shepherd

The UK study involved the use of two types of histamine receptor antagonists:

  • H1 antagonists: Loratidine or Fexofenadine
  • H2 antagonists: Famotidine or Nizatidine

H1 receptor antagonists reduce the release of histamine and are used to treat allergies. H2 receptor antagonists block the action of histamine on stomach cells and reduce the amount of stomach acid being produced. They are normally used to treat stomach ulcers and acid reflux/heartburn.

As with any preliminary finding from a study such as this, the treatment protocol now needs to be assessed in a much larger randomised clinical trail before any firm conclusions can be reached.

Additional information on Long Covid and ME/CFS

The ME Association has produced 40-page booklet covering information and guidance on all aspects of managing Long Covid symptoms that are also characteristic of ME/CFS and post-viral fatigue syndromes:

This booklet is a free download from the MEA website shop

Dr Charles Shepherd, Hon Medical Adviser, ME Association

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