Nausea and vomiting in cats with kidney disease

Many people are surprised to learn that cats with chronic kidney disease (CKD) often feel sick to their stomach. It can look like pickiness. It can look like a cat who is "just getting older." But very often, it is nausea — and nausea is something your vet can help with.

This guide explains why it happens, the quiet signs to watch for, what to write down, and when vomiting needs a call to your vet today.

Why kidney disease causes nausea

Healthy kidneys filter waste products out of the blood. When kidney function drops, some of those waste products build up. Vets call this buildup uremia. One of the best-known of these waste products is urea, which is measured on blood work as BUN.

These waste products can make a cat feel queasy in a few ways:

• They act on the part of the brain that triggers nausea and vomiting.
• They can irritate the lining of the stomach and mouth.
• Kidney disease can change how much acid the stomach makes, and how well the stomach lining protects itself.
• Dehydration, which is common in CKD, can make all of this feel stronger.

Nausea tends to be more common as kidney values rise, but cats are individuals. Some cats with fairly high numbers eat well. Others feel unwell earlier. That is why watching your own cat matters more than any single number.

The quiet signs of nausea

Cats rarely make a fuss when they feel sick. Vomiting is the obvious sign, but many nauseous cats never vomit at all. Look for these quieter clues:

• Lip-licking or smacking, especially near food.
• Drooling, or a damp chin.
• Walking up to the bowl, sniffing, and walking away. This is one of the most common signs. It often looks like your cat wants to eat but cannot.
• Eating a few bites and stopping.
• Crouching over the water bowl without drinking much.
• Swallowing hard or gulping.
• Grinding teeth or chewing oddly.
• Hiding, or sitting hunched with the head low.
• Suddenly preferring crunchy treats to their usual food, or the other way round.

If you see these signs, you are not imagining things. Tell your vet what you see. "She walks to the bowl and turns away" is very useful information.

Hairballs, food, or kidneys?

Not all vomiting is about the kidneys. Cats vomit for many reasons, and an older cat can have more than one thing going on.

• Hairballs usually look like a tube of fur with some fluid. Long-haired cats and cats who groom a lot have more of them.
• Eating too fast can bring food straight back up, often looking almost undigested.
• Food changes can upset the stomach, especially when switching quickly to a new diet.
• Other illnesses common in older cats, such as hyperthyroidism, inflammatory bowel disease, or constipation, can cause vomiting too.

Vomiting linked to kidney disease is often clear or yellow fluid, sometimes foamy, and often comes with a poor appetite. It may happen in the morning on an empty stomach. But the pattern varies, and only your vet can sort out the cause. Your job is to notice and record. Their job is to work out why.

Keep a simple log

A short log turns "she has been throwing up a bit" into something your vet can act on. For each episode, note:

• The date and time.
• What it looked like: food, fluid, foam, fur, or anything red or dark.
• Whether it was before or after a meal or medicine.
• Whether your cat ate afterwards.
• Any other signs that day: drooling, hiding, lip-licking.

A photo on your phone can help your vet too, unpleasant as that sounds. Our printable logs have space for notes, and the KidneyPaw app lets you log symptoms in a few taps so you can see patterns over weeks.

It also helps to bring your most recent blood work. If you have not looked at it closely yet, our Lab Decoder explains each value in plain English, including BUN, creatinine and phosphorus.

What your vet may suggest

The good news is that nausea in CKD cats is very often treatable. Many owners notice their cat starts eating again once nausea is under control. Your vet will choose what fits your cat, based on their exam, blood work, other conditions, and other medicines. Do not give any human medicine for nausea or heartburn without your vet's direction.

Some options your vet may discuss:

• Anti-nausea medicines. Maropitant and ondansetron are two that vets commonly use in cats. They work in different ways, and some cats do better on one than the other.
• Stomach acid reducers. Famotidine is one that vets sometimes use. Whether acid reducers help CKD cats is an area where vets have differing views, so ask what your vet recommends for your cat.
• Appetite support. If appetite stays low after nausea is treated, your vet may talk about appetite stimulants.
• Fluids. Correcting dehydration can help a cat feel better overall. Some cats receive subcutaneous fluids at home.
• Diet and phosphorus plan. Your vet may review your cat's food and phosphorus control, since these are part of long-term CKD care.
• Other tests. If vomiting is frequent or changes, your vet may want to check for other causes.

Follow your vet's instructions exactly for any medicine, including how much to give and how often. If a medicine seems to be causing problems, call your vet rather than stopping it on your own.

Small things that may help at home

These ideas will not replace treatment, but many owners find they help a nauseous cat feel more comfortable:

• Offer small, frequent meals rather than one or two big ones.
• Warm wet food slightly to around body temperature. Stir it well so there are no hot spots. Warmth makes food smell stronger and more tempting.
• Use a wide, shallow dish. Some cats dislike their whiskers touching the sides.
• Keep the eating spot calm and away from the litter box and noisy areas.
• Remove uneaten food after a while and offer fresh food later, instead of leaving a bowl that has gone stale.
• Do not force-feed unless your vet has shown you how and asked you to. Forcing food can create a lasting dislike of that food.
• Avoid introducing a new prescription diet while your cat feels sick. Cats can link the nausea to the food. Ask your vet about timing diet changes once your cat feels better.

If your cat refuses food entirely, read our guide on what to do when your CKD cat won't eat. In cats, going without food is a problem in itself, so do not wait too long to call.

When vomiting needs a call today

Kidney cats can become dehydrated quickly, and vomiting makes that more likely. Call your vet the same day, or an emergency clinic if your vet is closed, if you see:

• Blood in the vomit, or vomit that looks like coffee grounds.
• Vomiting three or more times in a day.
• Your cat cannot keep water down.
• Vomiting together with not eating, weakness, or hiding.
• No food eaten for more than 24 hours, or 12–24 hours with other signs of illness.
• A swollen or painful belly.
• Straining in the litter box with little or nothing coming out.

When you are unsure, call. Describe what you are seeing and your vet's team will tell you whether to come in. Our Is my cat okay? guide walks through these questions step by step, and it is always free.

The bottom line

Nausea is common in kidney cats, it is often hidden, and it is very often treatable. Watch for the quiet signs. Write down what you see. Tell your vet, even if it seems small. A cat who feels less queasy usually eats better — and a cat who eats is in a much stronger position for everything else in their care.

You are doing a good job by paying this much attention. That attention is exactly what helps.

Sources & further reading

• International Renal Interest Society (IRIS) — CKD staging and treatment recommendations
• Cornell Feline Health Center — Chronic kidney disease and vomiting in cats
• International Society of Feline Medicine (ISFM) / International Cat Care — Feline CKD guidance for owners and vets
• VCA Animal Hospitals — Client information on vomiting and kidney disease