First, is it possible to convince your doc to try a lower dose first, or to reduce the Metoprolol at lessen the effects of combining the meds?
If you find you absolutely cannot tolerate the Spironolactone, there are a few other medications, but I don't necessarily think they have less side effects. In addition, on most insurance, you must try and fail spiro first.

Good luck - I hope your body adjusts soon. This combination was difficult for my Mom when she was diagnosed with CHF.
Sue

Because of a rare birth defect in the heart 1 in a million and a birth problem with my pituitary gland plus other rare health issues. So my body has trouble trying to regulate my potassium level. Potassium helps to keep the heart running correctly but in my case, I either runs high or low. Many athletes know the effect of low potassium, severe muscle cramping in the calf. Now my Endocrinologist(hormone doctor) has me on 50mgs in the morning and 50mgs in the evening to help up my potassium level. The big problem falls on my shoulders, reading labels for potassium content on everything I put in my mouth.

That mistake about serving size almost killed me because the birth defect I have pushed me into tachycardia. So every day I walk a fine line between not enough salt in my blood from peeing to much or getting a potassium overload that will trigger the same problem, tachycardia which in my case will kill me because of my birth defect. So that’s why I have to take Spiro, my Doctor and I quickly learned 200mgs daily was way to much. So I have to adjust my intake from 50mgs daily, to 75 or 100mgs. It’s a vicious cycle, nothing like waking up in the morning with severe leg cramps in one or both calves before you even open your eyes because you peed out to much Potassium going to the bathroom in the middle of the night to many times. Yeah, loads of fun living in this “Freak of Nature” body of mine.