Inflammation is what closes airways and causes much suffering, to decrease it, take an antihistamine for allergies, and add a proton pump inhibitor such as pepcid ac, or omeprazole, stomach meds for gastric reflux also have strong antihistamine properties. I like Pepcid ac and Claritin 5mg 2x a day. NAC, N acytel systeine, awesome supplement, 900 mg, thins mucus, breaks down biofilms in bacteria, Quercitin with a strong Vitamin C, Zinc, fluids fluids fluids, crushed raw garlic, lemon juice, cayenne, honey, in a shot glass. Hot baths and steam, flush nose with saline. This is all good for any virus, bacterial infection, or chronic ailment. The addition of the pepcid, claritin, quercitin NAC, have greatly reduced my inflammation issues. Tell him to rest, thats when the body heals. He should be fine, what a person does for the flu, or the "covid virus" is the same, nothing different.