Does anyone know why Mercury -(Thimerosal) is used in Flu Vaccinations and where Mercuryisnot used Aluminium in other vaccines ? While these are known to be toxic metals, can these cause headaches, severe hot burning heads and or Sinusitus ?Thimerosal is not the same as mercury. It\'s a mercury-based preservative which to prevent the growth of germs, bacteria and fungi, that can contaminate them. It\'s used in seasonal flu vaccine because the vaccine is produced in large quantities and often in multi-dose vials. Thimerosal helps safeguard against possible contamination of the vial once it is opened. The aluminum in vaccines is aluminum hydroxide, aluminum phosphate, alum (potassium aluminum sulfate), or mixed aluminum salts. They\'re an adjuvant added to enhance the immune response in the vaccinated individual. Whether or not something is toxic has to do with how much a person receives not the substance itself. People can die from drinking too much water, but we don\'t go around calling water toxic. The amount of mercury or aluminum in vaccines is so small that it\'s not toxic. You ingest more mercury by eating fish and a baby ingest more aluminum in breast milk than they get in a vaccine. So if mercury and aluminum caused head aches, severe hot burning heads or sinusitis in a person, that person would have a lot more to worry about than vaccines since they would be exposed to those things in so many other ways.Toxicity is about dose. The dose of mercury in the flu vaccine is minute and cannot possibly contribute to mercury poisoning. In any case, Thimerosal converts to ethylmercury in the body which is quickly broken down and excreted - unlike methylmercury which is the mercury you are thinking about. A tuna fish sandwich will give you more mercury than any vaccine. Thimerosal is a preservative basically, which is why it is added to the multi-dose vial. If you are that paranoid about it, ask for the single dose vial to be used.It costs several cents more to manufacture 10 single dose vials that do not require mercury, than one multi-dose vial that does require mercury. Your health is worth just a few cents to these people. Aluminum is used in non-live virus vaccines in order to cause inflammation in the body, which produces a stronger immune response to the vaccine.Other related question