The H1/H2 histamine receptor blockade helps manage inflammation and overactive immune system for many people as they recover from Covid-19.
This may help you treat a temporary condition called Histamine intolerance. The H1/H2 blockade can help reduce your overall symptoms, including ones that are seemingly unrelated to your immune system.
Select one from the H1 category and one from the H2 category. You can find a full list here. Many are available over-the-counter.
Take them for a period of two weeks. If things are not getting better, select a different medication from the H1 or H2 list. Keep a journal of your symptoms over time. (I like to use an app called Bearable.)
Through trial-and-error, I found that Claritin and Pepcid AC were best for me -- but everyone is different. I no longer take Pepcid, but Claritin still helps reduce some symptoms.
Keep in mind that H1 blockers can cause drowsiness, so you might want to take them before a nap or before bedtime.
Also it may not be wise to take Pepcid long-term because of unwanted side effects. (I suspect I may have developed candida and C. Diff; taking Pepcid might have contributed.)
Some people report relief from taking a DAO supplement before meals. This is an enzyme that helps your body break-down histamine. Most of them have porcine kidney as the active ingredient. A common brand is Neurobiologix GI Hist Support, but others are available.