BD, my approach is to take what I need when i need it and not anything i dont need and not any more of what i need than is required. That includes antivirals and everything else. I got the improvement i needed and do not take them when i dont need them. It's all rat poison as one dr told me. Being 'natural' doesnt make a substance any less likely to cause unintended consequences. That is what i meant by the arsenic example. But if you want an herbal example think hemlock or white snakeroot.
I think it was arsenic that was rubbed into the pages of John III of Bavaria's prayer-book, killing him due to his habit of licking his fingers when turning pages. A Florance someone, if I remember correctly, was charged with poisoning her husband with arsenic during the turn of the 20th century, too. Though don't quote me on that. I'm attempting to climb neuroanatomy developed in 2001, during a very, very hazy sightseeing bus ride in London. Many random & contorted items lurking in that neck of my synaptic woods, undoubtably.
Hemlock, Tsuga canadensis, is a common, elegant evergreen tree, and is not poisonous. Poison hemolck, Conium maculatum, is a very poisonous weed, an invasive plant from Europe. --John of Ohio
^^ correct, in fact you can make a tea from the needles of the tree. The herb hemlock is very common, the flower looks a good bit like queen anne's lace.
Many herbs are both useful and poison. Poke weed for example. The tender spring leaves can be eaten if prepared properly but in maturity foliage and berries are poison. Roots are always very poison. Certain parts of the plant have been used as medicines by native americans and mountain folk. It's seldom all good or all bad in nature.