My reaction to red coloured ibuprofen is an insidious slowly building feeling of being unwell, stuffy head like the flu, but no nasal symptoms, and a queasy stomach like eaten too much rich food. The effect is slow growing over several days. When I stop the coloured ibuprofen it takes several days for the symptoms to clear up till I feel well again. It was difficult to diagnose. I have learned much of the last five years thanks to your work. When I take the white Brufen I am OK. The red ones were available on prescription thus cheaper but as I found out cheaper is not better. To get the right dose (200 mg) I take half a white tablet. – Steve, by email