An allergy to mold is your body's overreaction to the spores that mold releases in order to reproduce. Your immune system mistakenly tags mold as a dangerous substance, and once it does that, it will continue to make the same mistake forever. The idea behind allergy shots is to get your body used to the substance it thinks is dangerous so that it learns not to overreact when you come in contact with that substance in the future. Allergy shots are available to help you combat your mold allergy, although they're not considered as effective against mold as they are against pollen, insects and dust mites.
Allergy shots are typically recommended for people with severe allergies who suffer reactions for more than three months per year. However, they're not recommended for people who use certain medications, like beta blockers. They also might not be appropriate for pregnant women or women who intend to become pregnant in the near future. When you begin immunotherapy -- as allergy shots are known -- you are given a shot once or twice a week. As time goes by, the dose of the allergen in each shot is increased. Once you reach a maintenance dose and the shots seem to be working, you reduce the frequency of the shots to once every two to four weeks. This timetable can continue for up to five years. Allergy shots won't necessarily make your allergies go away completely, but they should help reduce the severity of your reactions to mold.
Since allergy shots contain extracts of the mold you're allergic to, there's a chance you'll develop an allergic reaction to the shots themselves. That's why most doctors ask you to remain in the office for a half-hour after your shot -- so they can monitor your reaction and intervene if necessary. It's normal to develop a red spot or swelling on the site of the injection itself.