The FDA warned that some people develop severe itching, or pruritus, after stopping long-term use of the antihistamines cetirizine (Zyrtec) or levocetirizine (Xyzal). Prescribing information for the ...
Niacin flush happens after taking 30-50 milligrams of niacin, causing redness and warmth. Other signs of niacin flush include itchy skin and tingling or burning sensations. Taking nicotinamide and ...