Why did my cat suddenly stop using the litter box?
Rule out a medical cause first — then look at the box itself: cleanliness, litter type, location, and count.
A house-trained cat that starts going outside the box is sending a message, not misbehaving. Painful urination from cystitis or lower urinary tract disease teaches a cat to associate the box with discomfort, so a sudden change in bathroom habits calls for a veterinary check before any behavior fix.
Health first, housekeeping second
One situation cannot wait: a male cat straining in the box and producing little or no urine may have a urethral blockage, which becomes life-threatening within a day or two — go to a clinic promptly. Once disease is excluded, audit the box: scoop daily, keep one more box than the number of cats, and place them in quiet, easily reached spots.
Litter preference is highly individual — many cats favor fine, unscented clumping litter, but texture and depth tolerance vary, and a recently changed brand is a common trigger. Reintroduce the old litter, and if the avoidance persists, consult your veterinarian about stress-related causes such as multi-cat tension.
MediIndex articles are for general information only and are not medical advice, diagnosis, or advertising. Outcomes vary by individual — consult a board-certified specialist for personal decisions.