I’m right in the middle of a nasty allergic reaction to my latest root touch up. 
Not dying is NOT an option, but weeping welts are not that cute, either. Anybody out there have a good suggestion for a hair dye that won’t make me look like I have a horrible disease?
Well… do you have any idea which component of the dye is causing the reaction? Unless you know what’s setting you off avoiding it will be hit or miss.
What color are you going for? Henna and cassia might be worth looking into.
My vote is for henna. I’ve been using it for awhile now… at least a year? It’s a permanent red gloss over your existing color, and it’s non-chemical. Works well to spruce up my mousy brown, and makes my silvering roots look like highlights over the darker bits. Only con is the odor, and the process is quite messy. My husband puts it on my hair once every couple of months, though, it’s a nice bonding thing.
No matter what you try or think you could use, you HAVE to do a spot test 48 hours before you apply dye to your head. For someone with such allergic problems, I’m not sure why you’re not doing this. Even if you’ve used it before, you need to do the spot test. Every time.
Better, would be to get allergy tested and find out the ingredient(s) causing the problem and go from there. That still doesn’t exempt doing the spot test every time before you dye. Salon dyes tend to be gentler sometimes than drug store packaged stuff. If you’re allergic to an ingredient in the boxed stuff, you may need to check out places like Sally Beauty Supply for the individually packaged components.
I like using henna, too; it’s also a great conditioner for your hair.
If you’re worried about henna being too brightly red, you can chase a dyeing session with an indigo dye. I tend to mix the two, with a greater ratio of indigo, but if you do henna followed by indigo, you can get nice, rich browns. The whole process takes me about two, two and a half hours, on a Saturday afternoon every 6-8 weeks or so.
Deffo test strands, though, as other posters have suggested.
Beat me to it. Most people are not allergic to plant-based dyes, but as with anything, patch test first.
Good info here on various plant dyes and combos for just about any hair color: http://hennaforhair.com/
The likely culprit is Paraphenylenediamine (PPD), which is in most commercial hair dyes, even demi and semi permanent. You can develop a sensitivity over time.
If you don’t want to mess with henna/cassia/indigo, you can try one of the PPD free specialty dyes out there. EcoColors is one example.
I’ve gotten it down to 15 mess free minutes for waist length hair. I’m about to do it know, in fact, as soon as I’m done posting this! 3 “secrets”: I now get my henna from Henna Color Lab. Their stuff needs no acid, just warm water, and it doesn’t need an overnight color release. Don’t ask me, it’s magic. (Yes, it’s real henna.) Two, as directed, I wash my hair first and put the paste on damp hair, which makes it spread more quickly and evenly. And third and most importantly, get yourself an irrigation syringe. Amsino Flat Top Piston Syringe at HealthyKin.com Suck and squirt, making parts with the tip every half inch. It’s phenomenally faster than any brushes or clog prone squirt bottles I’ve tried, and I’ve tried 'em all.
I’ll have it all on and wrapped in a shower cap and Turbie Twist in 15 minutes, then I’ll go to bed on an old pillowcase and rinse it out in the morning. Really, it only needs to sit for an hour, but it’s late and I’m ready to go to bed. Being henna, it can’t sit too long and fry my hair off!
I mix mine in a big batch every six months or so. 2 packets of jamilla henna, I can of coconut milk, some water, and a splash of vinegar. Wait overnight, then freeze in in small ziploc bags. When I’m ready to do my roots, I thaw a bag and cut the tip off it to use like an icing bag. It’s pretty unmessy and quick. And cheap.
This year one of the farmers market vendors was selling specialty beer mustard in typical mustard bottles like you see in diners. After finishing a bottle off, I realized that it would be about perfect for dispensing henna, so I tried it. Mixed it right in the bottle, and you can put the cap on the tip and shake to get it mixed well. It also went much MUCH faster and with less mess and drippiness than the icing bag approach. I also, somehow, end up using less henna paste for the same coverage.
I also leave it on overnight but I like a nice rich color. My hair is auburn to begin with, but medium-to-dark, so the henna gives the red highlights a nice lift.