Pyridostigmine bromide (PB) is a drug used as a pretreatment for potential nerve agent exposure. An estimated 250,000 troops took PB during the Gulf War. Since 1994, VA and DoD have funded 30 projects related to the health effects of PB, alone or in combination with other chemicals or stressful stimuli. Eighteen of the 30 projects focus on potential interactions between PB and other agents. One consistent result of the recent studies is that stressful stimuli do not cause PB to cross the blood-brain barrier (BBB). This contrasts with a 1996 study in which early research in this area indicated increased permeability of the BBB due to swimming stress in a particular strain of mice. Several more recent studies have failed to reproduce this finding using a variety of species, a variety of stressful stimuli, and extremely high doses of PB. If PB does not cross the BBB, it is very unlikely to cause changes in brain function.

A Review of the Scientific Literature as it Pertains to Gulf War Illnesses: Volume 2 Pyridostigmine Bromide. This report by the RAND Corporation examines the safety and effectiveness of PB used during the Gulf War as a pretreatment to protect military personnel from the nerve agent soman. The review was performed to identify hypotheses or theories that might link PB to illnesses in Gulf War veterans. Although medical research has not established PB as a cause of Gulf War illnesses, the report maintains that it "cannot be ruled out as a possible contributor to the development of unexplained or undiagnosed illnesses in some PGW [Persian Gulf War] veterans."

Gulf War and Health Volume I: Depleted Uranium, Sarin, Pyridostigmine Bromide, and Vaccines. In response to concerns raised by veterans, the Department of Veterans Affairs (VA) approached the National Academy of Sciences and requested that the Institute of Medicine (IOM) conduct a study to evaluate the published scientific literature about adverse health effects from the agents to which the Gulf War veterans may have been exposed. The committee decided to select the compounds of most concern to the veterans: depleted uranium, chemical warfare agents (sarin and cyclosarin), pyridostigmine bromide, and vaccines (anthrax and botulinum toxoid). The IOM concluded in its report that there is "inadequate/insufficient evidence" to determine whether an association exists between PB and long-term adverse health effects.

Pyridostigmine Bromide Intake During the Persian Gulf War Not Associated with Postwar Handgrip Strength. This research, done by the Naval Health Research Center, suggests that servicemembers who took PB during the Gulf War experienced no loss of strength as a result. In order to learn if PB use is related to physical strength, researchers administered a standard handgrip test to 527 Gulf War veterans and 969 non-deployed veterans.