Taser International, which makes weapons that fire up to 50,000 volts and are used to incapacitate a person, also said it would no longer claim in its consumer literature that its guns "left no lasting effects".
The voluntary concessions come after the attorney general of Arizona, where Taser is based, launched an investigation earlier this year into claims made by the firm about safety studies carried out on its products. It is among nearly two dozen states that have started action against Taser products in recent months.
The Taser president, Tom Smith, said company officials had met with the attorney general's office several times since January and have made changes to the way they present information on the weapon to consumers.
"We are trying to give consumers more clarification as to what some of the terms used in our marketing and product information mean," said Mr Smith. "We have had 22 states introduce various forms of legislation restricting the sale and use of Tasers to consumers this year.
"We have suggested many of the restrictions ourselves, such as a ban against people under 18 buying them. I do not think it is going to have any effect on sales."
According to the firm, the stun-gun maker submitted a list of voluntary language changes to the attorney general's office that include an 18-point "product warning".
Mr Smith also said that Taser uses the term "non-lethal" as defined by the US Department of Defence - which does not mean the weapon cannot cause death, but that it is not intended to be fatal.
Other changes include substituting the phrase "leave no lasting after-effects" to "are more effective and safer than other use-of-force options".
Consumers can purchase Taser guns in all but seven US states, though the introduction of background checks and other restrictions in some states has coincided with a sales slump. Revenue almost halved between the final three months of last year and the first quarter of 2005.
A Taser device was used by police in Birmingham during the arrest of one of the men charged with attempted murder following the failed London bombing attempt on July 21.
Sir Ian Blair, the Metropolitan police commissioner, expressed alarm over the use of the Taser gun in the arrest. He said that if the man had been wired with explosives, the electrical charge could have set them off.
Last month, a man who tried to force his way past a barrier at Manchester airport was brought down with one of the weapons before being arrested.
Last year, all firearms officers were given Home Office permission to use them. A spokeswoman for the Association of Chief Police Officers said British authorities "did not call Tasers non-lethal and never had done". Instead they are referred to as "less lethal" than other methods of detaining people.
Taser claims its weapons "save lives everyday" by providing police forces with a method for stopping and detaining people that carries less risk of serious injury than using conventional firearms, truncheons or dogs.
After the Birmingham arrest in August, Mr Smith told the Guardian: "We were really proud of that. We had employees crying. For us to have made a product to assist in making sure he doesn't do that to anyone else - to capture him and be able to get information out of him - it was a great day."
The weapons have been credited for that fact that no fatal police shootings took place in either Miami or Seattle in 2003, the first time that had happened in over 12 years.
But the Chicago police force, which already has 200 Taser guns, delayed deployment of further weapons in February after a 14-year-old suffered a heart attack and a 54-year-old man died. Taser maintains that no deaths have been directly caused by the weapon alone.
During a year-long trial carried out by five British police forces, no serious injuries resulted from the 58 occasions Taser guns were used, but in 2001, Home Office researchers discovered people who had been in contact with CS gas were at "serious risk" of catching fire if a Taser gun was subsequently used. Many officers are told to use CS gas to resolve a situation before employing a more extreme method such as a Taser.
