Hello and Welcome to ‘Ask A Doctor’ service. I have reviewed your query and here is my advice. Immediate medical attention is only required if associated with the rash are severe itchiness, chest tightness, and swelling of the skin. All these signify an allergic reaction to dayquil/nyquil which could get dangerous. However, stopping the drug was the best course of action as the rash might have indicated the onset of an allergic reaction. If there are no other symptoms besides the rash, I would advise you take over-the-counter antihistamines such as Benadryl for relief. You do not need to see a doctor unless the rash remains unabated after a few days treatment or if other symptoms, as mentioned above, occur. Hope I have answered your query. Let me know if I can assist you further. Regards, Dr. Greg Okhifun