My medication alkalizes urine and can cause calcium phosphate stones. how can i acidify my urine to counter this effect?

Acidifying urine: You can acidify urine by taking vitamin c or cranberry juice. Certain foods can acidify the urine too, such as plums, prunes, meats, cheeses, eggs, fish, and grains.

Add citrate: Best approach is to add citrate. Citrate interferes with ca x phos and ca x oxalate. Citrate is available by rx as Urocit K and as Bicitra (citric acid and sodium citrate). You can supply citrate with orange juice and ReaLemon extract. These will not alkalinize urine.