What are you using for a parasite clease? Most herbs are safe if taken in the correct dose for not too long of a period. The only anti- parasite herb that I've heard as being dangerous is Wormwood , and thats if its take for a long period of time. There may be others I've not heard of.
A drink called "Absynth" used to be made from Wormwood . Note that there are 2 types of Wormwood , one has Absynthium, the other doesn't. The one without is called Sweet Wormwood I think and is much safer.
You could go to a doctor that does muscle testing ( kinesiology ) and check if you react to it. I would not worry too much however, if you don't have an existing medical condition AND you are not taking any prescription medications. IF you have a medical condition OR you are taking prescriptions I would not do anything without consulting a doctor.
Otherwise, have you had your liver numbers checked? AST/ALT? If those are fine, you are probably ok.
I don't understand your concern with alcohol. The herbal tintures are strong ( 20-50% alcohol ), but you only take a couple drops. If you have no history with bad reactions to alcohol you should be fine. If you still concerned, you can heat some water in a glass ( like you are making tea ) in the microwave until its steaming and ALMOST boiling. Then take it out and put the herbal tinture in it. Wait several minutes for the mixture to cool. The alcohol will evaporate.
1. Most prescription and OTC drugs are as dangerous if not more so than herbs. Acetaminophen, which is in many pain relief medicines causes more cases of liver failure than herbs. Many prescription drugs can cause liver problems. Thats why doctors frequently give you a blood test every few months when on a strong prescription. The want to make sure your liver isn't blowing up.
2. parasites make many toxins, which are probably more damaging to your body than herbs are.
3. If your taking a parasite remedy you bought in a health food store, chances are at least several other thousand people have taken them without problems. I've taken several things, and my Liver numbers are fine. In fact, all my numbers are fine, because I have the parasites "In Check" at the moment. My Liver numbers were much worse when I was put on some prescription medicines before I figured out about the parasites and they though I had "Gland" problems.
4. I had 8 fillings removed and a root canal done. The parasites and the mercury go hand in hand. I did the mercury removal first, but thats before I figured out about the parasites. I don't think having 1 filling will be that much of a problem. But you might want to get testing to see if you sensitive to Amalgam ( Copper, Tin, Silver, Nickel, Mercury ).
5. Try an extremely small dose at first and see how you do.
If you are really concerned, you can start with "food" type parasite remedies and Supplements. These are what I've found works. But they may not completely rid you of your problem. I've tried several things, and I'm finally getting rid of them using my own mix of herbs and foods.