Concepts for Anti-crowd Weaponry

15 Minute Lice
Shotgun shells  filled with sterile (non-reproductive) lice genetically altered to live for a short period of time. The would also be bred for rapacity and the ability to cause discomfort. Shortly before use, the lice can be re-hydrated by the user to revive them, then fired at rioters or combatants.

15-minute lice can also be used as an interrogation aid.

Cellphone bombs
You know there has to be a way to make them explode remotely, especially since some of them do it spontaneously anyway. If you could hit the enemy with some kind of directed-energy weapon that only worked on cellphone batteries, you could knock out their communications and cause alarm/discomfort simultaneously. Granted they would adapt eventually, but at first there would be confusion and panic.

Unpleasant Sounds
The sound of nails on chalkboard, or pieces of styrofoam rubbing together. Figure out what it is about those things that affect people, isolate and amplify. Even if the noises don’t bother everybody they will bother enough people to cause confusion and reduced effectiveness.

Penis Shrinkers
Find a drug that causes penis shrinkage. I realize that since science cannot find one that does the opposite it may be a while before anything like this shows up, but I guarantee this will cause enough terror among the enemy that they comply with your wishes or send female soldiers.

Toothless predators
Lions, crocodiles, polar bears, all bred to have no teeth and kept hungry (fed small portions of human flesh every day). With no teeth and no claws they lack the ability to cause serious injury but are hungry so they try anyway, chasing people and gumming them. This is especially useful in First World riot situations where the protesters are likely to be animal-rights types who will not hurt the animals.