I appreciate that you have done your bit of homework on the medication.. Yes your worry is genuine. Hydrochlorthiazide does come with a warning label that it may exacerbate systemic lupus erythematosis. It is also documented as one of the causal agents of drug induced lupus. Now since that is what you already know, let s think of a practical solution for your hypertension. As you already have lupus, I assume that there would be some amount of lupus nephritis( kidneys being affected because of lupus). You can check it by getting your 24 hr urine protein quantified. In that scenario, the best drug in my opinion would be an ACE inhibitor.. it shal kill both your enemies with one sword. The other available and safe option for you is nifedipine.. I would recommend you to discuss the same with your treating physician.. Do feel free to discuss if you have any further queries Thanks