cough and nasal congestion
"Musinex D worked great to clear up my chest congestion that two rounds of antibiotics didn't touch. But I didn't know that a side effect was insomnia. So, although I started feeling better soon after taking it last night, I was well aware of how good I was feeling right on up to 3am!  I asked the pharmacist at our local store if Musinex D could have caused the insomnia, and she said yes, and not to take it at night."