Sulfonamides (Bactrim, Bactrim DS, Septra, Septra DS) (cont.)

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Many of these drugs are available only in generic forms.

What drugs interact with sulfonamides?

Sulfonamides can increase the blood-thinning effects of warfarin (Coumadin), possibly leading to abnormal bleeding.

The increased metabolism (break-down and elimination) of cyclosporine by the liver caused by sulfonamides (reduces the effectiveness of cyclosporine and can add to the kidney damage caused by cyclosporine.

All sulfonamides can crystallize in the urine when the urine is acidic. Since methenamine (Hiprex, Urex, Mandelamine) causes acidic urine, it should not be used with sulfonamides.

Blood levels of digoxin may increase blood levels of digoxin (Lanoxin) and possibly lead to serious toxic effects.

Anemia, due to a reduction in folic acid, can occur in persons receiving sulfonamides in combination with divalproex, valproic acid (Depakote, Depakote ER, Depakene, Depacon, Stavzor), methotrexate (Rheumatrex, Trexall), pyrimethamine, triamterene, or trimetrexate.

Medically Reviewed by a Doctor on 3/27/2015

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