Bear spray contains a lower levels (typically 1-2%) of oleoresin capsicum than pepper sprays intended for self-defense against human assailants (typically 10% or greater) and should not be used as self defense as it is much less effective. 
Studies suggest that bear spray is effective at reducing the risk of injury or death in these situations. Bear spray is statistically more effective than the use of firearms in preventing and reducing human injury, and is additionally a non-lethal deterrent for bears. While bear spray can be effective, authorities stress that proper bear-awareness and avoidance techniques are the best ways to minimize injuries due to human-bear conflict.
Mark Matheny claims to have developed the first capsaicin product designed specifically for use against bears following a 1992 near-lethal encounter with a bear which he survived using standard pepper spray. After the attack, he became determined to develop a pepper spray that would work more effectively against bears by increasing the potency, range, and duration of the deterrent. Today Matheny's bear spray is sold under the name UDAP, and many other capsaicin bear sprays are commercially available.
Bear spray is intended to be used to deter an aggressive or charging bear. A user points the canister at an aggressive bear and sprays the contents for at least 6 seconds. The recommended minimum distance between the user and bear is 25 feet. Using the spray improperly can have undesirable effects. Because the deterrent effect depends on the bear receiving a concentrated dose of spray, using bear spray on objects or clothing is not effective, and can actually attract bears.
Because spray canisters are pressurized and contain hazardous contents, they must be stored in cool temperatures and handled with care. They can explode from overheating if left on a car dashboard. A typical can of bear spray costs about $40 to $50 USD. Bear spray is available to rent in some tourist destinations, such as Glacier National Park and Yellowstone National Park.
Bear spray is a very effective deterrent when used properly. In a 2008 review of bear attacks in Alaska from 1985–2006, Smith et al. found that bear spray stopped a bear's "undesirable behavior" in 92% of cases. Further, 98% of persons using bear spray in close-range encounters escaped uninjured.
The efficacy of bear spray depends on the situation and circumstances of the attack. In the 2008 study, Tom Smith of Brigham Young University reported, “No bear spray has ever been reported to kill a bear. It is our belief that widespread use of bear spray will promote human safety and bear conservation.” On the other hand, latent spray (on object) has also led to the attraction of bears, which usually end up with the bear destroying the spray-covered object. This serves as a need to cautiously manage deterrent distribution and is a good example of where spray is useful and where it is not.
A United States Geological Survey article, “Bear Spray Safety Program,” says that bear spray is effective in fending off aggressive bears while also preventing injury to both the human and the bear. It also states, “No deterrent is 100-percent effective.” In "Living with Grizzlies," the U.S. Fish and Wildlife Service states, “The Service supports the pepper spray policy of the Interagency Grizzly bear Committee, which states that bear spray is not a substitute for following proper bear avoidance safety techniques, and that bear spray should be used as a deterrent only in an aggressive or attacking confrontation with a bear.”
Bear spray is legal across the United States. It can be purchased even in Hawaii, New York, or Massachusetts, where standard pepper sprays are illegal unless bought locally by certified firearms dealers or pharmacists. Bear spray is illegal in some National Parks, but Glacier and Yellowstone National Parks encourage bearspray in the backcountry as grizzly bears reside there.
- Blome, Charles. "Bear Spray Safety Program" (PDF). U.S. geological Survey. Retrieved 27 Mar 2012.
- Smith, Tom S. et al. (2008). "Efficacy of Bear Deterrent Spray in Alaska" (PDF). The Journal of Wildlife Management 72 (3): 640–645. doi:10.2193/2006-452. Retrieved 27 Mar 2012.
- Frank Miniter. The Ultimate Mans Survival Guide. Retrieved July 19, 2014.
- Matheny, Mark. "The Story of Mark Matheny: A grizzly bear attack survivor". www.udap.com. Retrieved 23 August 2014.
- "Be Bear Aware: Bear Spray". Center for Wildlife Information. Retrieved 23 August 2014.
- "Bear Spray Rentals". Keystone Conservation. Retrieved 23 August 2014.
- U.S. Fish and Wildlife Service. "Bear Spray vs. Bullets" (PDF). Retrieved 30 Mar 2012.
- "Pepper Spray Laws". loyaldefender.com. Retrieved 2014-04-09.
- "Yosemite National Park, California - Weapons/Firearms". U.S. National Park Service. Retrieved 21 Jun 2013.