Why Is My Cat's Pee Green? Color Changes Explained

Name: Why Is My Cat's Pee Green? Color Changes Explained
Creator: Dr. Zubair Khalid

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-10-03

Green urine in cats is uncommon and usually points to something in the diet, a medication or supplement, or a problem in the liver, bile system, or urinary tract. In many cases the color change is harmless and short lived, but green urine can also be the first visible sign of a serious medical issue. This article is educational and is not a substitute for veterinary diagnosis or treatment.

Quick Answer

Green urine is often linked to diet, food dyes, or certain medications and supplements, so check what your cat has eaten or been given recently.
A liver or bile problem can turn urine green or greenish brown, and that needs same day veterinary attention.
Urinary tract infections and other urinary issues can change urine color and odor, so testing is the only way to know for sure.
If your cat is straining, crying, or producing little or no urine, treat it as an emergency and go to a vet now.
Bring a fresh urine sample in a clean container if you can, and note any new foods, treats, or medications.

What Normal Cat Urine Looks Like

Normal cat urine is clear to pale yellow. The exact shade shifts with how concentrated the urine is. A well hydrated cat often produces pale, dilute urine, while a cat that is not drinking much produces darker yellow urine.

Urine color is a rough clue about concentration, but it is not a reliable measurement on its own. In dogs, urine color was positively correlated with urine specific gravity, yet about 20% of dark yellow samples still had a specific gravity below 1.030, meaning color alone missed how dilute the sample really was [1]. The same caution applies to cats. Color is a starting point, not a diagnosis.

Several things change urine color without meaning disease. Blood can tint urine pink or red. Bilirubin can make it orange or brown. Dilution makes it paler. So when you see green, the question is what is adding that color or what is happening inside the body to produce it.

Cat Pee Green: The Main Causes

Green urine has a short list of common explanations. Some are harmless. Some are not.

Cause	Typical clues	How urgent
Food dyes or colored treats	Green urine started after a new food, treat, or dyed product. Cat acts normal.	Routine visit if it persists more than a day or two
Medications and supplements	Recent new drug, supplement, or dewormer. Color change follows dosing.	Call your vet to confirm, usually not an emergency
Liver or bile disease	Green or greenish brown urine, yellow tint to gums or eyes, vomiting, poor appetite, weight loss	Same day, urgent
Urinary tract infection	Strong odor, frequent small urinations, straining, licking the genital area, accidents outside the box	Same day to next day
Urinary blockage (male cats)	Straining with little or no urine, crying, hiding, vomiting, lethargy	Emergency now
Blood contamination	Pink to red to brown urine, sometimes with clots	Same day, urgent if the cat seems unwell

Diet and Food Dyes

The simplest reason for green urine is what your cat ate. Some commercial foods, treats, and dental products contain dyes that pass into urine. If the color change lines up with a new product and your cat is eating, drinking, and acting normally, diet is a reasonable first suspect. Stop the new product and watch. If the color clears within a day or two, diet was likely the cause.

Medications and Supplements

Certain drugs and supplements can discolor urine. Some antibiotics, some pain medications, and various vitamin or herbal products have been reported to change urine color. If your cat started a new medication and the urine turned green, call the prescribing veterinarian. Do not stop a prescribed medication on your own. Ask whether the color change is expected and whether the drug needs to be changed.

Liver and Bile Problems

The liver makes bile, and bile contains pigments that are yellow green. When the liver or bile ducts are not working normally, those pigments can build up in the blood and spill into urine. This is one of the more serious reasons for green urine. Watch for yellow tinge to the gums, the whites of the eyes, or the skin. Other signs include vomiting, refusing food, weight loss, and low energy. These cats need blood work and a veterinary exam promptly.

Urinary Tract Infection and Inflammation

Infection and inflammation change urine in several ways. You may notice a stronger smell, more frequent trips to the box with smaller amounts, straining, or accidents outside the litter box. A urinary tract infection does not always change color, but when it does, the change can be green, cloudy, or bloody. A urine test confirms it. If your cat is also urinating outside the box, that behavior can have both medical and behavioral causes, and it is worth reading about Why Is My Cat Suddenly Peeing on the Carpet? so you can tell the difference.

Blood in the Urine

Blood contamination changes urine color and can also change test results. In one study, any blood in a urine sample significantly increased dipstick scores for blood in both dogs and cats, and visible blood contamination also affected bilirubin and ketone scores, pH, and specific gravity [2]. That matters because a colored sample sent to the lab can give misleading results. Tell your vet if you saw blood, and let them decide how to collect and interpret the sample.

Blood in the urine can come from stones, infection, inflammation, or trauma. In male cats with urethral obstruction, darker red urine at the time of catheter placement was linked to more significant metabolic problems, including higher creatinine and potassium levels, and those cats often needed more aggressive supportive care [3]. Color alone did not predict whether stones were present, so imaging is still needed [3].

Urinary Blockage

A blocked cat cannot pass urine. This is a life threatening emergency, most common in male cats. Signs include straining in the litter box with little or nothing coming out, crying out, pacing, hiding, vomiting, and becoming weak. If you see this, go to a veterinary emergency hospital immediately. Do not wait to see if it passes.

Red Flags That Mean Emergency

Some signs mean you should stop reading and call a veterinarian or emergency clinic now.

Your cat is straining to urinate and producing little or no urine.
Your cat is crying, howling, or pacing near the litter box.
Your cat is vomiting, weak, or collapsing.
Your cat's gums, eyes, or skin look yellow.
Your cat has not urinated in 12 or more hours.
Your cat is a male cat with a history of urinary blockage.

For poison exposure questions, call the ASPCA Animal Poison Control Center at (888) 426-4435 or the Pet Poison Helpline at (855) 764-7661. These lines may charge a consultation fee.

What You Can Safely Do at Home

You cannot diagnose green urine at home, but you can gather useful information.

Collect a fresh urine sample in a clean, dry container if your cat will let you. A clean ladle or a shallow clean container under the stream works. Refrigerate it and bring it to the visit.
Write down everything your cat ate or was given in the last 48 hours, including treats, table food, supplements, and medications.
Note the litter box habits. How often? How much? Any straining, crying, or accidents?
Check the gums and eyes for a yellow tint in good lighting.
Offer fresh water and keep the litter box clean so you can monitor output.
Do not give any human medication, and do not change prescribed doses on your own.

If your cat is acting normal and only the color changed, a routine visit within a day or two is reasonable. If any red flag is present, go now.

What Your Veterinarian Will Check

Your vet will start with a full physical exam, including hydration, gum color, abdominal palpation, and bladder size. A very large, firm bladder in a straining male cat points to blockage.

Testing usually includes:

Urinalysis, which checks color, concentration, pH, blood, protein, crystals, and infection.
A urine culture if infection is suspected.
Blood work, including liver values, kidney values, and electrolytes.
Imaging such as X-rays or ultrasound if stones, blockage, or bladder abnormalities are suspected.

If your cat is blocked, treatment involves relieving the obstruction and supportive care. One study looked at whether leaving a urinary catheter in place affected the risk of the blockage coming back within 30 days. In that study, 11% of cats in the inpatient group had a recurrent obstruction [4]. Your vet will weigh the risks and benefits of catheter placement and hospitalization for your individual cat.

Urine color can also be a clue to how sick a cat is. In blocked male cats, darker red urine correlated with higher creatinine and potassium and lower urine specific gravity [3]. That is why your vet may repeat blood work during treatment.

If your cat has ongoing urinary or litter box issues, including peeing in unusual places, these articles can help you sort out medical from behavioral causes: Why Is My Cat Suddenly Peeing on My Clothes? and Why Is My Cat Peeing on the Rug? Medical and Behavioral Reasons.

Preventing and Monitoring Urine Color Changes

You cannot prevent every cause of green urine, but you can lower the odds and catch problems early.

Keep your cat well hydrated. Fresh water daily, and consider a water fountain if your cat likes moving water.
Feed a consistent, balanced diet. Introduce new foods slowly and one at a time so you can spot reactions.
Keep the litter box clean and in a quiet spot. One box per cat plus one is a good rule.
Watch the box. Notice color, clumping size, frequency, and odor.
Schedule routine wellness visits. Blood work and urinalysis catch liver and kidney changes before you see them at home.
Tell your vet about every supplement, even ones labeled natural. Some affect urine color and some affect lab results.
If your cat has a history of urinary problems, ask your vet how often to recheck urine.

Limitations and When to Contact a Veterinarian

Urine color is a clue, not a diagnosis. Many conditions that change urine color look identical to the eye, and some serious problems cause no color change at all. Only a veterinarian can examine your cat, test the urine, and interpret the results in context.

Call or go in the same day if you see green urine along with vomiting, poor appetite, weight loss, yellow gums or eyes, or a cat that seems painful or dull.

Go to an emergency clinic now if your cat is straining to urinate with little or no output, crying in the litter box, vomiting repeatedly, or collapsing. A blocked cat can die within a day or two without treatment.

Schedule a routine visit within a day or two if the only change is urine color and your cat is eating, drinking, and acting normally. Bring a fresh sample and a list of foods and medications.

Every cat is different, and individual cases need a veterinarian who can examine your cat and run the right tests.

Frequently Asked Questions

Can food really turn my cat's pee green?

Yes, food dyes and colored treats can pass into urine and turn it green. If the change started with a new food or treat and your cat seems well, stop the product and watch for a day or two. If the color does not clear or your cat shows other signs, call your vet.

Is green cat pee always a sign of liver disease?

No, liver and bile problems are one cause among several. Diet, medications, supplements, and urinary infections can also change urine color. Yellow gums or eyes, vomiting, and poor appetite raise the concern for liver involvement and need prompt testing.

Should I collect a urine sample before my vet visit?

Yes, a fresh sample is very helpful if you can get one cleanly. Use a clean, dry container and refrigerate it until the appointment. Even if you cannot collect a sample, note the color, odor, and how often your cat urinates so your vet has that information.

My cat seems fine but the urine is green. Can I wait?

If your cat is eating, drinking, and acting normally, a routine visit within a day or two is reasonable. Do not wait if you see straining, crying, vomiting, yellow gums, or a cat that hides and seems painful. Those signs mean same day or emergency care.

Can green urine come back after treatment?

It can if the underlying cause is not fully resolved, such as an ongoing liver issue or a urinary problem that needs monitoring. Ask your vet how often to recheck urine and blood work. Keep watching the litter box at home so you notice changes early.

References

Correlation between urine color and urine specific gravity in dogs: Can urine color be used to identify concentrated urine?. The Canadian veterinary journal = La revue veterinaire canadienne, 2018.
Effect of blood contamination on results of dipstick evaluation and urine protein-to-urine creatinine ratio for urine samples from dogs and cats. American journal of veterinary research, 2018.
Correlation of gross urine color with diagnostic findings in male cats with naturally occurring urethral obstruction. Journal of feline medicine and surgery, 2015.
Evaluation for association between indwelling urethral catheter placement and risk of recurrent urethral obstruction in cats. Journal of the American Veterinary Medical Association, 2018.