Hi there,
It's possible the Gan Cao in LJZT is contributing to the rise in blood pressure, but should not be, if the Kidney tonics are doing their job properly. In other words, the hypertension is not so much evidence of an adverse event, but an incomplete effect.
Normally Rehmannia reduces renal and systemic hypertension through multiple mechanisms, but it looks like the renal blood flow effects of Epimedium Formula are too weak, possibly because Rehmannia is only a minor player in the formula. I'd suggest going with Rehmannia Eight, where the percentage of Rehmannia is much higher and would be expected to reduce hypertension more easily, possibly even allowing use of some Six Gentlemen. Note, though, that Rehmannia Eight tonifies Source Qi, which the Spleen can then utilize to power digestion. Specific Spleen tonics are not often necessary in these cases, then, but the Fu Ling and Shan Yao in Rehmannia Eight safely support healthy digestion all the same
Hope that helps
Steve