The development of capsaicin bear spray took place in the mid 1980s under principal investigator Carrie Hunt, a University of Montana graduate student working under the supervision of Dr. Charles Jonkel and Dr. Bart O’Gara. Hunt had identified commercial pepper sprays as an effective, but unreliable deterrent for bears in previous research; however, these products were only effective inconsistently and required short distances. Hunt's thesis was published by the U.S. Fish and Wildlife Service in 1984. Bill Pounds, who eventually founded Counter Assault bear spray, assisted Hunt and offered to help prototype a reliable aerosol bear spray canister for Hunt's research. They developed a bear spray formula with a spray range of over 30 feet and a spray time of over 7 seconds. Pounds played an important part in developing the ingredients, the dispersal system, and the recommended specifications of bear spray. The company he founded, Counter Assault, became the first Environmental Protection Agency registered aerosol bear spray.
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 2–3 seconds. Effective distance will vary depending on the manufacturer of the spray, but sprays are reported to be effective when sprayed at a charging or aggressive bear from a distance of 1.5 to 3 meters (4 ft 11 in to 9 ft 10 in).
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.
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.”
Studies suggest that bear spray is effective at reducing the risk of injury or death in these situations. 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.
A 2008 "Efficacy of Bear Deterrent Spray in Alaska" study stated:
- "Red pepper spray stopped bears’ undesirable behavior 92% of the time when used on brown bears, 90% for black bears, and 100% for polar bears.
- Of all persons carrying sprays, 98% were uninjured by bears in close-range encounters.
- All bear-inflicted injuries (n = 3) associated with defensive spraying involved brown bears and were relatively minor (i.e., no hospitalization required).
- In 7% (5 of 71) of bear spray incidents, wind was reported to have interfered with spray accuracy, although it reached the bear in all cases.
- In 14% (10 of 71) of bear spray incidents, users reported the spray having had negative side effects upon themselves, ranging from minor irritation (11%, 8 of 71) to near incapacitation (3%, 2 of 71).
- Bear spray represents an effective alternative to lethal force and should be considered as an option for personal safety for those recreating and working in bear country."
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. In Canada, while legal for use against bears, bear spray is a prohibited weapon if intended to be used against humans.
Bear sprays are considered a pesticide in the US and must be registered with the Environmental Protection Agency. The capsaicin in products sold in the U.S. are regulated by the Environmental Protection Agency, under the FIFRA act by Congress. 
- Blome, Charles. "Bear Spray Safety Program" (PDF). U.S. geological Survey. Retrieved 27 Mar 2012.
- ROGERS, LYNN L. (1984). "Reactions of free-ranging black bears to capsaicin spray" (PDF). Wildl. Soc. Bull. 12: 59–61.
- "Bear Spray Fact Sheet" (docx). Be Bear Aware Campaign. Retrieved 25 June 2018.
- "Meet the man who changed humans' relationship with bears". High Country News. Retrieved 25 June 2018.
- "Bear Spray Works". bebearaware.org. The Be Bear Aware Campaign. p. 10. Retrieved 30 June 2018.
- "Interagency Grizzly Bear Committee Bear Spray Report June 2008" (PDF). Be Bear Aware Campaign. p. 12. Retrieved 25 June 2018.
- "BEHAVIORAL RESPONSES OF BEARS TO TESTS OF REPELLENTS, DETERRENTS, AND AVERSIVE CONDITIONING" (PDF). University of Montana. p. 4. Retrieved 25 June 2018.
- "Interagency Grizzly Bear Committee Bear Spray Report June 2008" (PDF). Be Bear Aware Campaign. p. 13. Retrieved 25 June 2018.
- "Pepper Spray Frequently Asked Questions". Sabre.
- Wilkinson, Todd; 25, National Geographic PUBLISHED September. "How a Potent Pepper Spray Became the Best Bear Repellent". National Geographic News. Retrieved 2015-09-26.CS1 maint: numeric names: authors list (link)
- 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. Archived from the original (PDF) on 26 December 2011. Retrieved 27 Mar 2012.
- U.S. Fish and Wildlife Service. "Bear Spray vs. Bullets" (PDF). Retrieved 30 Mar 2012.
- "Efficacy of Bear Deterrent Spray in Alaska" (PDF). doi:10.2193/2006-452. Archived from the original (PDF) on 2011-12-26.
- "Yellowstone Launches Bear Spray Campaign". Times-News. Twin Falls, Idaho. June 1, 2016. Retrieved October 4, 2019.
- "Pepper Spray Laws". loyaldefender.com. Retrieved 2014-04-09.
- Bell, Danielle (5 February 2014). "Rules confusing around bear, pepper spray". Ottawa Sun. Retrieved 12 November 2015.
- "Bears - Glacier National Park". U.S. National Park Service.
- "Selecting Proper Bear Spray". Yellowstone National Park. U.S. National Park Service.
- "Yosemite National Park, California - Weapons/Firearms". U.S. National Park Service. Retrieved 21 Jun 2013.
- "Be Bear Aware - Bear Spray". www.bebearaware.org.
- "Be Bear Aware, Bear Spray". Be Bear Aware.