I really only use their Stevia but would have no problem with the Wormwood because as far as I know they try to deliver a quality product. Here is their website- http://www.nowcatalog.com/

I have that tincture. It can also be used for enemas, but I believe it is a good product for parasites. I use many of their products and have never had a problem. If you get the chance, try their Plant Enzymes product, that really helped me with many digestive issues before I found my allergies. And digestive enzymes are very helpful in helping to break down the parasites both before and after they die. Bromelain is really good for that. NOW has a Quercetin/Bromelain product that is very good.

I use Intestinal Support by Eclectic Institute. Several sites have recommended it, and I have used it for a parasite cleanse before. It is very easy as it does the job with 3 capsules a day(6 for the first week after a ramp up period), and is excellent for a maintenance program. I also add a bit of the Kroeger Cloves to give it an extra punch.