The vasovagal syncope trigger causes your heart rate and blood pressure to drop suddenly. That leads to reduced blood flow to your brain, causing you to briefly lose consciousness.
Vasovagal syncope is usually harmless and requires no treatment. But it's possible you may injure yourself during a vasovagal syncope episode. Your doctor may recommend tests to rule out more serious causes of fainting, such as heart disorders.
There are two flu vaccines that don't contain egg proteins, approved for use in adults age 18 and older. And even flu vaccines that do have egg proteins can be given safely to most people with egg allergy.
If you've had a reaction to eggs in the past, talk to your doctor before getting a flu vaccination. Your doctor may choose to give you the vaccine made without eggs or send you to a physician who specializes in allergies.
A skin test may be needed to see if you're truly allergic to eggs. A nurse or doctor will scratch a tiny amount of egg protein on your skin and watch to see if your skin reacts to it.
If the skin test is positive, you'll still probably be able to get the flu vaccine. Your doctor may want you to wait 30 minutes before leaving, in case you have a reaction.