Diarrhoea after pill

Patient: I just started taking the pill (Rigevidon). About two hours after taking it for the first time I had diarrhoea and felt sick. My friend who has been taking the pill for years said that this could mean that that particular pill isn’t working for me. Is this so? Is there any way to know if it is working?

Symptoms: Diarrhoea, nausea, stomach upset