I didn't read all the responses yet, but I'd say that "herx" is often used interchangeably for "herx" and for "flares". I know I've made that mistake in the past personally.
I have only been able to identify a few true herx for us that were related to treatment. Honestly, I have kids who are ALL OVER THE BOARD with symptoms that it's very difficult to correlate.
I'd say that they "flare" more than they "herx".
We rarely see improvement after a flare or herx.
EXCEPT for Kid#2. He appears to be very reactive to some things. For the antiviral supplements, he will definitely herx when he first starts them or when I increase dosage, and then he's MUCH MUCH MUCH better in symptoms when he's been on the supplements for a few days. It's very identifiable and repeatedable (is that a word? LOL).
Many times he will initially react to a new herbals, but it certainly doesn't mean it will be better for him in regards to symptoms. : | (Our naturopath suspects it's more of a chemical reaction than a true improvement from herbals, but the jury is still out for me on this for him.)
Also, I've had herbals cause major flare-ups of symptoms I did NOT even have previously/currently. In some cases, I'd stop the herbals and would take months for symptoms to resolve. In other cases, I continue on the herbals and again takes months for symptoms to resolve (if they even do). I definitely feel these are flare-ups and not necessarily herxs (although I'd suspect many others would call them herxs).
I guess I'm really no help on this one!
Kid#1: Extremely sick for several years, very difficult to treat, but doing great now!
Kid#2: Very sick now despite being treated for years, still very bad
Kid#3: Generally good but relapsing off/on.
Me: Adv Labs positive 2016 (suspected I passed to my kids)-not as sick as others, mostly battling fatigue and yeast issues (heart/kidney issues resolved)
Treating with herbals now.