I don't see why they couldn't be taken together, they have completely different uses. Teasel never did anyrhing for me, Buhner says it works for about half of the people who take it. Pinella-burbur didn't do much for me either, actually.
IR saunas, epsom salt baths and occasional binders are most effective for alleviating herxes for me but we are all different. For some, burbur and teasel are highly effective, i see no problem in trying them. Do you think he may have any coinfections?