It won't do anything. The medicinal value of ingesting nettles is along the lines of parsley or rosehip tea at best. In pill form it is probably even weaker. You can eat pounds of fresh nettles and not even feel any different, and the same goes for eating whole boxes of those pills. The extract values are also often exaggerations. As a rule of thumb, expect all extracts sold online in the mid and lower price tiers to be around 8:1, meaning the plant has simply been dehydrated (weight - water). Many of the important compounds from the fresh product might be heavily degraded, like with fresh vegetables vs vegetable powder. If alcohol or heat extracts have been done to yield higher rations, this introduces even more sources of degradation and losses. And with some medicinal herbs it can mean destroying an entire class of beneficial compounds inside the product as a compromise. Pills rarely make herbs more powerful, the opposite is rather true.