According to what you said, if you have backache due to yang deficiency, you can take Zhuangyao Shen Jian Pill orally under the guidance of a doctor.

Suggestion:

Thirst after taking Zhuangyao Shen Jian Pills is generally related to the drug being too warm. So I suggest you go to the hospital to see if it is caused by kidney yin deficiency or kidney yang deficiency. If it is caused by kidney yin deficiency, stop using this medicine and cooperate with Liuwei Dihuang Pill to relieve the symptoms of backache. If it is caused by kidney-yang deficiency and thirst is serious, you can consider taking it in a reduced amount.