Chlorcyclizine / phenylephrine
"I was told to take one tab per day for environmental allergies. That was too much. I developed a splitting headache after use. So I began taking just 1/2 tab and that works well. The basic side effect for me is a "cloggy" throat. My voice sounds as if I need to clear my throat in a very big way. It does keep the allergy symptoms at bay."