Dear person who googled "coughing and cannot stop" (without the quotes) and found my little site,
I am so sorry that you or someone you know is coughing and can't stop. Believe me, I know how that feels. It sucks. And it sucks to be the person watching the cougher. Just ask Dave. :( I find Robitussin works really well, but please, for the love of whatever deity you hold holy...if the cough doesn't go away in a week or so, CALL THE DOCTOR. The cougher may have pneumonia. And if s/he does, s/he needs to go on antibiotics as fast as s/he can get on them. Not because it helps them heal faster (although it does) but because this mean that the taste of death is over sooner, rather than later. For example, if I had gone to the doctor when everyone was looking at me and going, "Dude...you should really see a doctor..." two weeks ago, I could have been finished the pills that cause my mouth to taste like death over a week ago! And that would have been a glorious thing.
To recap: Sorry. That sucks. Try Robitussin for a week or less. Go to the doctor. Take nasty tasting pills ASAP. Be finished nasty pills and be finished with nasty taste AND the sickness!
PS. They might tell you it's a virus. Call them on it. Ask how they know. They told me it was a virus for nine months. Guess what. The antibiotics are working, BEEE-YATCHES.