Here is the basic sulfonamide group molecule, the basis of "sulfa" drugs:

Here is the molecule for the common diuretic Hydrochlorothiazide:

Here is the Spironolactone molecule:

You will notice they are quite different. Furthermore, if the mere presence of sulfur in a molecule bothers you, please stop eating onions, leeks, chives, garlic, broccoli, cauliflower, Brussels sprouts, cabbage, kale, asparagus, sweet potatoes, and tomatoes.
And don't forget, beef, chicken, fish, most nuts and legumes. Oh, and pineapple, banana, avocado, grapefruit, and watermelon.
One more thing - don't sweat. Human sweat and urine contain thiols (mercaptans) and other sulfur-based metabolites which give them its scent.
Dawn Heart, if you are really interested in the subject, talk to your pharmacist and find out the course-load he or she took to more fully understand elements of biochemistry.
Here is my non-medical opinion. because I have allergies to some medications too. If you start by taking a small dose of Spironolactone and if you break out in hives, call you doctor. That is what the list of contraindications says on the printouts I get with every prescription. That will probably be what your pharmacist will tell you too.
"A little knowledge is dangerous."