My cat growls and hisses at me for no reason. She used to be affectionate.

Four months of this, intermittent and unpredictable, in a cat who used to be affectionate, is something I would want to look at medically before anything else. Pain is the most common reason a cat who was previously comfortable with human contact becomes reactive, and pain in cats is notoriously easy to miss because they are very good at masking it. The fact that she is sometimes completely normal and comes to sit with you is consistent with intermittent pain, the kind that is worse on some days than others, or triggered by certain movements or positions.

I would not wait on the vet visit. I know it seems behavioral but unpredictable reactivity that started at a specific point in time, in a previously affectionate cat, is a pattern I take seriously as a possible pain signal. Dental disease, arthritis, and internal conditions that cause intermittent discomfort can all present exactly this way.

If the vet clears her physically, then we look at environmental triggers, changes in the sensory environment, stressors outside the home, or shifts in household routine that might be affecting her sense of safety. The Work With Me assessment walks through both the behavioral and environmental picture in a way that often surfaces what is being missed, and I would be glad to help you think through it once you have had her checked.