Don’t think that if one dose of medicine is good, two doses must be better or try to combine them in ways that haven’t been physician-approved. You risk having side effects that can complicate your recovery.
In general, it is better to use medications that target one specific symptom — decongestants for nose; cough medicines for cough and NSAIDs (non-steroidal anti-inflammatory drugs) for pain. The multiple symptom medications may contain drugs you don’t need, which ups the chance of side effects (dizziness, diarrhea, insomnia, headache or nausea). These side effects can make it harder for you to bounce back when you are already fighting a viral infection.
“In general, such medications may not work as well after a few days of regular use, but it is not predictable and is very variable,” said Dr. Aaron Glatt, executive vice president and chief administrative officer for New York's Mercy Medical Center and a spokesman for the Infectious Diseases Society of America.
One more thing: If your nose is congested, you can use decongestant nasal spray, but if you use it for more than five days, it can cause a rebound effect, meaning your congestion may actually get worse. (You may want to try saline nasal mist instead.)