Is my cat's shedding normal or a sign of illness?

I have been watching River, my five-year-old mix, for the last few weeks. He is usually very calm, but he has lost noticeable patches of fur on his flanks. Quiet, my seven-year-old tabby, has started shedding heavily too, though she is shy and I only see it when she grooms herself. I am worried this is more than just seasonal change. I have a background in writing, so I tend to overthink the narrative of our lives together, but this feels like a plot point I don't want to ignore. What are the common medical causes of excessive shedding that would require a vet visit? I want to be sure I am not missing something serious before I just brush them more.

River, I am so sorry you are worrying. As a social worker, I know that anxiety can be transferred to the animals, so try to stay calm for them. My Dot, a three-year-old tabby, had a similar scare last year. It turned out to be stress-induced shedding because she is quite anxious. However, you are right to look for medical causes. There is a great thread here that breaks down the medical side: Medical causes of excessive shedding. It lists things like thyroid issues or parasites. I would check for fleas first, just in case, even if you don't see them.

My Rocco is a five-year-old American Shorthair and he is so cuddly that I brush him every day, but he still sheds a lot. I remember reading that diet plays a big part. KarenT wrote about this in her thread: Raw feeding and coat issues. She suggests that raw feeding may reduce coat issues, but I am not sure if that is safe for every cat. I also saw kathy_simmons struggling with the same thing in her post about Excessive shedding in my shorthair. She uses a vacuum a lot. Maybe you should look at the grooming tools too? dana.young has a post on Rubber grooming tools for shedding that I found helpful, though I am not sure if it fixes the root cause.

I travel a lot for work, so I am always worried about my cat, Rex, a ten-year-old Maine Coon. He has weight gain issues, which I think might be related to his coat? I have seen that stress from being alone can cause shedding. But I am not a vet. I think you should really check the pinned thread that threerescues mentioned. It is the most reliable source here. I am just guessing based on my own experience, so please don't take my word for it over a professional's.

As a teacher, I like to have organized information. I am not a veterinarian, but I have dealt with health issues for my Siamese, Whiskers, who is eight and has stage 1 CKD. Her coat changed when her kidneys started acting up. I would definitely call your vet today if you see bald patches, redness, or if the cat is scratching a lot. angela.ross asked a similar question before about checking for skin conditions. I think the best step is to take photos of the patches to show the vet. The thread Medical causes of excessive shedding is a good starting point for what to look for, but it is not a diagnosis.

I am a nurse, but I overthink everything about my cats, Loki and Freya. Loki is a one-year-old Bengal and is so energetic, he rubs against the furniture constantly. Freya is a one-year-old Ragdoll and is very calm. I used to worry that all shedding was bad, but joan.webb said her Ragdoll sheds less after switching to a humidifier. Maybe the dry air is affecting River and Quiet? I am not sure if that is a medical cause or just an environmental one. I feel like I am missing the connection between the grooming tools and the medical issues. Can someone clarify if the rubber tools in Rubber grooming tools for shedding actually help with medical shedding or just remove loose hair?