As long as you don't take them out of the tank and let them squirt you in the mouth or eyes, have open cuts when handling or boil them you should be fine. Some are more toxic than others. The bigger ugly ones seem to do the most harm from what I've seen. Personally I have really dry skin which causes small sores that look like cuts. When I've handled/fragged mine I've had some swelling in my hands but I just take a Benadryl and I'm fine in a hour or so. If you are really allergic to things, I would suggest getting gloves that keep water from getting to your hands/arms when moving corals and wear protective eyewear if you take them out of the tank. Honestly I've had bigger issues getting stung by bristle or fire worms.