None that I am aware of, but for the sake of providing information and not making any assumptions, here's what the website says:
Tanalbit®, potential side effects and contraindications
Tanalbit® is a non-toxic, herbal supplement. Tanalbit® works indirectly in the body and so side-effects are very minimal, if any. Some symptoms that some may experience are constipation and nausea and occasionally, die-off. The tannins in the Tanalbit® may cause constipation in some, and if this occurs, we suggest taking a Magnesium Supplement and/or a tablespoon of apple cider vinegar to alleviate constipation and help with digestion, in addition to increasing water intake (by at least 2x's as much).
In cases of nausea, we suggest first eating some food with the dosage, and if this does not help, then reducing the dosage. (AGAIN, please consult your health professional before changing your dosage). According to the PDR for herbal medicine, one of the plant components of Tanalbit®, Quebracho extract, sometimes can cause mild dizziness, nausea or sweats in very sensitive individuals. If this occurs, consider altering your regimen (either by consuming food w/capsule or lowering dosage), and consult your health provider.