[rhondalea]

Sensitivity can develop after the first exposure to a substance and grow worse over time.

This is why the L'Oreal box warns us to do a patch test every single time we cover our roots. It's also why I was able to take Bactrim intermittently until I was in my early 30s, and then--KABOOM!!--I woke up in the middle of the night bright red all over my body and thinking I would likely die of itching. I also have an acquired allergy to tea tree oil that occurred about 2 years after first use.

As for doctors, I must confess to a "what have you done for me lately?" attitude. That may not be the best approach, but I've had some very dismissive doctors in my lifetime. As a result, I was untreated for severe Hashimoto's for years. I was also erroneously diagnosed with MS. (I only avoided treatment for MS because I was so sure I didn't have it, I walked out on the doctor who diagnosed me. The next doctor in line looked at me like I was a loon when I asked for a thyroid panel, but he never apologized for treating me like a nutjob when the results came back.)

I have learned the hard way that we need to trust our instincts about our doctor's care for us, and when we start getting that bad feeling in the pit of our stomach, it's time to move on.

My bias is that my brain hurts, and I'm pretty pissed at the medical profession right now, so except for the factual item in the first paragraph, you might want to take me with a grain of salt.