Do allergy injections have mercury in them?

Allergy injections, also known as allergy shots or immunotherapy, do not contain mercury. Mercury-containing preservatives, such as thimerosal, were historically used in some vaccines to prevent contamination and extend shelf life. However, thimerosal has been largely phased out due to safety concerns, and it is no longer used in allergy injections or any widely recommended childhood vaccines in the United States.