I had the most terrible cough this winter, and this Robitussin Long-Acting Cough was the ONLY thing I found that actually worked. It did take about a half an hour to kick in, but once it did, my coughing was almost gone and I was able to live my life. It lasted a full 8 hours. Once the 8 hours was up, my cough did return immediately, so it didn't actually heal me. But I was so impressed that it worked as well as it did for those 8 hours. I also like that it was non-drowsy (something that was hard for me to find in a cough medicine). It meant that I could use this medicine to get me through the day. I used Nyquil one night because I thought it would work better, but I found that I was up every few hours. This Robitussin allowed me to sleep 8 hours straight because it supressed my cough completely!