When you go to the store to buy an over-the-counter bed bug spray, be sure to check out the ingredients. Deltamethrin is a powerful pyrethroid; however, most bed bugs have developed one or two mutations of resistance against it, so the chemical has lost much of its effectiveness. Permethrin is approved for fighting ticks and fleas but not for fighting bed bugs. Piperonyl butoxide is a pesticide synergist which has no innate pesticide activity. However, when added to other ingredients such as pyrethroids or carbamates, it can enhance their power.
Search on the interne for each ingredient to find out what its current anti-bed bug fighting ability really is.