What is good for children's coughs?

My child has a cough and a cold, but fortunately, there is no fever.

I finished all the medicine the hospital gave me, but my cough is still bad.

When I had a cold before, I heard that Ophiopogon japonicus was good, so I bought some granular medicine from the pharmacy and gave it to my child. It worked well, so I stocked up on it and gave it to them, but this time, it doesn't seem to have much effect, perhaps because they developed some kind of resistance.

If I wake up in the middle of the night and start coughing, drinking water doesn't help.

Sigh... that's pitiful.

Have you tried feeding this to your child and seen any results?