What can I do about the foul smell coming from my shower drain?

Dump some vinegar and baking soda down it, let it bubble.

I removed drain cover, cleaned out yuck, and poured vinegar & baking soda in drain, rinsed with hot water, replaced drain cover. Smell gone.

https://www.reference.com/home-garden/rid-shower-drain-smell-cd6446572e92c

Janet your link doesn't seem to work.

It seems like vinegar and baking soda is the winning combo for this problem: http://www.hometalk.com/diy/clean/appliances/q-how-to-get-rid-of-funky-odor-from-the-shower-drain--25337907

A plumber friend told me that those liquid body soaps in the squeeze bottles,

(especially if you use more than one kind), can leave foul smells in your drain. I know this sounds weird but I stopped using them and the smell went away, it worked for me!

Thanks for all the suggestions!

This may be a strange question but ... do you have a second shower or tub you use instead of the "smelly one"? If so, the solution might be the same as what happened to me. I have one bathroom I use every day and another (for guests) so it's used infrequently. I was told the odor is gases that are coming up through the drain (when there's no water in the pipe below the drain) and to eliminate that, simply let the water run for say, a good 30 seconds (so water is replaced in the curvy pipe below the drain). I now run water in my sink AND bathtub/shower drain(s) once a month and the odor has never returned. With the other bathroom, there's no problem as it is used every day.

PS: if you only have the one bathroom, I'm sorry the above advice is of little use!

Not sure if I'm typing in the right spot but for Jan Mahony, Columbus, the following occurred to me: we had a bad storm (6 months ago) with incredibly high winds. I mentioned that I noticed we had a nasty odor to a pretty skilled handyman who said that high winds can sometimes displace the small amount of water that is in a curved part of pipe below the drain (tub/shower/etc). If the water becomes "pulled" away, then odors will rise into the bathroom as there's no water in the pipe. On a very windy day, have you ever noticed the water in the toilet bowl moving a little bit? That's what happens below the surface; where we can't see. I don't know if Karen of Plano, TX has one or two bathrooms. If she has just one bathroom, then this isn't her problem. But for any bathroom that isn't used much at all, once a month, I'd run the water for just under a minute in the sink and tub/shower - anywhere there is a drain.