MiraLax for Cats: Dosage, Side Effects, Risks, and More

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Reviewed by Diana Wells

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Before we start discussing using MiraLax for cats, let’s explain what MiraLax is, its benefits, and its side effects. It is important to clarify that it is an FDA-approved drug for use in people, not cats. So, you must consult your veterinarian before administering MiraLax to your cat.

Medication Overview

MiraLax for Cats

TypeOsmotic Laxative
FormPowder for oral administration. Available in different-sized bottles
EffectsMiraLax is a human medication that can also treat constipation in cats. It works by softening stool and making it easier for cats to defecate.
Intestinal obstruction
Kidney disease
Prescription Required
FDA ApprovalApproved for humans. Not approved for use in cats
MiraLax, ClearLax, GaviLax, GlycoLax, PEG 3350, HealthyLax

What is MiraLax for Cats?

MiraLax, an over-the-counter laxative, is safe for cats, but consult a vet first. It contains polyethylene glycol 3350 (PEG 3350), which softens stools by increasing colon water content.

Unlike stimulant laxatives, it doesn’t contract colon muscles, making it gentle on feline intestines. Improving gastrointestinal health, MiraLax relieves constipation in cats and removes toxins, which is vital for cat well-being.

MiraLax Dosages for Cats

MiraLax is a human medicine. Thus, there is no official MiraLax dose for cats. The standard dosage for constipated cats will vary depending on the cat’s weight, the severity of constipation, and whether the cat has any underlying disease.

The following dosage chart is a general guide.

Cat’s WeightSeverityHow Much MiraLax to Give a Cat
<10 poundsLess severe
⅛  Teaspoon 1-2 times daily 
Very severe¼  Teaspoon 1-2 times daily 
>10 poundsLess severe
¼ Teaspoon 1-2 times daily 
Very severe½  Teaspoon 1-2 times daily 

Please note that the chart mentioned above is not a substitute for veterinary recommendations.

Consult your veterinarian for the appropriate MiraLax dosage tailored to your cat’s medical history. Monitor your cat’s response post-treatment to gauge effectiveness, assessing bowel movement frequency and consistency and observing any changes in behavior.

If necessary, adjust the dosage under veterinary guidance. Should MiraLax prove ineffective, consider exploring alternative options. Consistent follow-up is key to ensuring optimal management of cat constipation.


As we know, cats have difficulty when it comes to taking medication. It can even result in a fight with their owner. But with MiraLax for cats, it is a different story. The following means of administration can be applied:

Wet Cat Food

Since it’s tasteless and odorless, most cats ingest it without realizing it. All you have to do is mix it with a tasty snack such as Smalls Ground Bird Fresh Cat Food .

Another recommended wet cat food brand for constipation is

Open Farm Homestead Turkey Rustic Blend Wet Cat Food

Dry Cat Food

MiraLax can also be incorporated into dry cat food brands.

Open Farm Homestead Turkey & Chicken Dry Cat Food

Open Farm Kitten Grain-Free Dry Cat Food

Hill’s Prescription Diet Gastrointestinal Biome Digestive/Fiber Care with Chicken Dry Cat Food, Veterinary Diet, 4 lb. Bag
  • Hill’s Prescription Diet Gastrointestinal Biome Digestive/Fiber Care with Chicken Dry Cat food is specially formulated by Hill’s nutritionists and veterinarians to support your cat’s digestive health
  • Helps firm loose stools in 24 hours

As MiraLax is an osmotic laxative, it absorbs water into the intestine. Here are tips for using it effectively:

  1. Mix a small amount of wet food (one tablespoon) with MiraLax, diluted with water.
  2. Before giving the medicated food, offer a small portion without MiraLax to avoid suspicion.
  3. Administer the mixture, followed by the remaining wet food.
  4. Alternatively, dissolve MiraLax in a small amount of water in the cat’s bowl, although control over intake is limited.
  5. Ensure multiple water sources are available to prevent cat dehydration, including pet water fountains and bone broth infused with MiraLax.

Harvest Chicken Bone Broth for Cats

If your cat is still reluctant to take the medication, the remaining option is to mix the dose of MiraLax in 1 ml to 2 ml of drinking water in a spoon and then load it into a syringe without a needle. Administer in the mouth. Take appropriate measures to avoid bites and scratches.

MiraLax for Cats – Side Effects

Only one study published in 2011 evaluated the safety and palatability of polyethylene glycol 3350 as an oral laxative in six cats over four weeks. As a result, no cats exhibited changes in body weight or food intake. 

Soft stools occurred in all cats studied. The effective doses varied among cats, so individualized dosing is important. The cats evaluated tolerated the medication without side effects, but one cat developed sporadic vomiting. Much information and studies still lack the exact side effects in cats on MiraLax [1]

As side effects of administering MiraLax for cats, we can observe: 

  • Nausea.
  • Vomiting.
  • Increased bowel movements.

Side effects are of sporadic occurrence. MiraLax rarely causes discomfort in cats when administered at the correct dosage.

Adverse effects that may occur after the administration of MiraLax result from an overdose.

Overdose and Allergy Signs

MiraLax for cats is not a product that can generate life-threatening allergies or fulminant problems. Some signs include:

  • Explosive, watery diarrhea
  • Intestinal rumbling and abdominal discomfort
  • Flatulence
  • Sometimes, vomiting
  • Dehydration and electrolyte imbalance: This is the most severe damage that MiraLax in cats can cause. If you suspect your cat has become dehydrated, consult your veterinarian. Your cat may need intravenous fluids to recover. And, of course, a change of MiraLax dosage.

Storage Instructions

Store feline MiraLax at room temperature, between 68-77°F (20-25°C), in a dry place with low humidity.

Do not use the product if the foil seal under the cap is missing, opened, or broken. Once opened, do not refrigerate the medicine and keep it in the medicine cabinet.

Keeping the medicine in its original container is important because it is child-resistant, and its opacity prevents sunlight.

Do not use expired medications; discard them.

It is important to keep the bottle of MiraLax out of children’s and pets’ reach. In case of accidental ingestion, contact the ASPCA poison control center immediately.

When disposing of MiraLax, do not flush it down the toilet or pour it down the drain, as it may contaminate the water supply. Instead, dispose of the medication in the trash. Mix it with an unpleasant substance, such as coffee or kitty litter, to discourage animals from ingesting it. Place the mixture in a closed plastic bag and throw it in the trash.

When is MiraLax for Cats Not an Option?

In a cat with constipation episodes of more than two to three weeks, do not use MiraLax. It is likely that a cat with repeated episodes of constipation has a more serious health problem, such as an obstructive disease, cancer, etc., and will need more tests (e.g., ultrasound, blood tests, x-rays, etc.) to become diagnosed and specific treatment applied.

Avoid laxatives if a cat ingests foreign objects like threads or toys to prevent bowel stimulation that could worsen the damage. Emergency surgery is often necessary for foreign body treatment. Cats may develop fecalomas and hard fecal masses, causing obstruction and abdominal discomfort.

Detecting constipation early is crucial to prevent feline fecaloma formation; however, MiraLax becomes ineffective in such cases. A veterinarian may attempt enemas to break up masses, but surgery is often required for removal.

Do not administer MiraLax to dehydrated cats, as it can exacerbate dehydration; instead, use intravenous saline for rehydration. Early detection and treatment of fecalomas are essential to prevent further complications.

Associated Risks

Improper use of MiraLax for cats can harm their health, especially with high doses, posing risks for patients with certain medical conditions.

Older cats with kidney failure are particularly vulnerable to dehydration and medication retention due to impaired kidney function.

  • Never give MiraLax with other medications, as it will decrease their absorption.
  • Do not give MiraLax together with another laxative.
  • Never use MiraLax if the cat receives diuretics or similar since the risk of dehydration is high.
  • Do not give MiraLax to cats with endocrine pathologies that cause electrolyte imbalances.

Alternatives to MiraLax

For MiraLax alternatives, consider:

  • Increasing dietary fiber through commercial foods or supplements like canned pumpkin or oat bran.
  • Prescription option: Lactulose, a laxative similar to MiraLax.
  • Addressing hairballs with products like Cat Lax or Laxatone, which help them move through the digestive tract.
  • Encouraging exercise, preventing pet obesity, maintaining dietary consistency, and regular veterinary check-ups are also vital.

That’s a Wrap

Every cat is different, and what works for one may not work for another. If your cat suffers from constipation, it is best to consult your trusted veterinarian to determine the best way to solve the problem. MiraLax for cats is a great way to solve mild constipation in our feline companions.

Is MiraLax Safe for Cats?

Yes, MiraLax is a safe medication. It is available over-the-counter in an odorless, tasteless powder form and is easy to give to cats to treat mild to moderate constipation. Discuss using MiraLax with your veterinarian before giving it to your cat.

How Quickly Does MiraLax Work for Cats?

MiraLax generally begins to work in cats within 12 to 72 hours. Yet, seeing the full effect may take up to 48 hours.

What if I Miss a Dose of MiraLax?

The indications for administering MiraLax in cats are once or twice a day as needed. But, if you forget to give a dose, it is not a serious problem. Resume the treatment plan stipulated by your veterinarian. Do not increase the dose or give two doses of MiraLax concurrently.

How Long Can Cats Take MiraLax?

Use MiraLax only for short-term treatment of constipation in cats. If your cat has constipation for more than two to three weeks, your veterinarian will need to do tests to detect the specific cause. 
If your cat’s stool is heavily impacted, it may require an enema. Long-term use can not only cause dehydration but could result in low sodium and high potassium levels, adding more complications to the diagnosis.

Can MiraLax Be Used for Cats With Chronic Constipation?

MiraLax in cats does not work for chronic constipation. In these cases, the veterinarian will investigate the specific cause of the obstruction blocking the passage of feces. 

Can MiraLax Be Mixed With Dry Cat Food?

For dry food, sprinkle MiraLax on the cat’s kibble. Medicating a small portion of food ensures the cat eats it.

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With a veterinary master's degree from the University of Copenhagen in 2023, this accomplished writer's academic journey culminated in a thesis focused on the "Feasibility of using ultrasound of the abdomen for early diagnosis of necrotizing enterocolitis in neonatal pigs." Additionally, their dissertation delved into the intriguing topic of "Mercury accumulation in Greenlandic sleddogs." Beyond her academic achievements, her passion for animal health seamlessly merges with her love for writing. She excels in harmonizing clinical precision with literary expression, crafting articles that resonate with the heartbeat of her veterinary profession.