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Miralax for Cats: Is it Safe?

Sick cat laying on an orange cushion
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Medication details

  • Medication type: Laxative, Bowel cleansing agent
  • Form: Powder for oral soluation
  • Prescription required? Available with and without a prescription
  • FDA approved? No
  • Life stage: All
  • Brand names: Miralax, ClearLax, GaviLAX, Gialax, GlycoLax, PEG3350, SunMark, ClearLax, HealthyLax, CoLyte, GoLytely, NuLytely, MoviPrep
  • Common names: Polyethylene glycol 3350, PEG 3350
  • Available dosages: OTC products are available in either pre-measured 17 g packets or bulk powder.

Constipation is a common and uncomfortable problem for humans, as 20 percent of the general population experience this issue [1]. Miralax is a laxative medication readily available and used to treat constipation in humans. This medication has also become popular in treating constipation in our feline friends

In this article, we will explain what Miralax is, whether or not it is safe to use in cats, what conditions it treats, how to administer it to cats, its common side effects, and dosing information. 

What is Miralax? 

Cat looking up with slight head tilt

Miralax is an osmotic laxative, which means it draws water into the intestines to soften stools, stimulating bowel movements and easing constipation. The active ingredient in Miralax is polyethylene glycol 3350, or PEG 3350. In 1999, the FDA approved Miralax for use in humans to treat occasional constipation. The product was approved for over-the-counter use in 2006 [2]. 

Most recommended forms of this medication are available to pet parents without a prescription from their local pharmacy. Formulations of PEG 3350 that contain added electrolytes are only available with a prescription. The version of Miralax that is used for cats is the same as the human product.  

Is Miralax Safe for Cats?

Cat sitting in a litter box

Miralax is generally considered a safe medication to give to cats. However, it is always best to confirm with your veterinarian that it is okay to give Miralax to your cat. Miralax should not be given to cats that are dehydrated, as it can lead to further dehydration and electrolyte abnormalities. 

Cats suspected of having gastrointestinal obstruction, gastric retention, bowel perforation, toxic colitis, or ileus should also not be given Miralax. PEG 3350 solutions containing electrolytes (eg, CoLyte®, GoLytely®) should be used with caution in cats with inflammatory bowel disease.

What is Miralax Used For in Cats? 

Miralax is most commonly used to relieve and treat constipation in cats. Prescription PEG 3350 containing electrolytes is mostly used to clean out the bowels before endoscopy procedures and to help flush toxins out of the gastrointestinal tract for cats that have eaten something harmful. There are no other currently recommended uses for Miralax in cats. 

In humans, Miralax has recently been found to be more effective than lactulose for treating hepatic encephalopathy (a nervous system disorder brought on by liver disease). Miralax may be useful to treat this condition in cats, but studies are lacking [3]. 

How to Give Miralax to Cats

Cat eating wet food from a bowl with miralax mixed in

Miralax comes in a powdered form meant to be dissolved in liquid. However, it is okay to give the powder to cats as long as it is mixed with food, preferably canned or wet food. The powder is tasteless and odorless, so most cats will take Miralax without a fuss. 

When Miralax is used to treat severe constipation or in preparation for an endoscopy procedure, it is generally administered as a liquid solution. It must be given by a trained veterinary professional. 

Miralax Side Effects in Cats

Cat stretching out on a bench

To date, there is only one published study that evaluated the use and safety of Miralax in six cats over 4 weeks. For this reason, side effects are not well known. In the published study, most cats tolerated the medication without side effects, but one cat developed sporadic vomiting [4]. 

Besides vomiting, nausea and cramping are possible side effects of giving cats Miralax. 

It is thought that long-term use of Miralax may cause dehydration, low sodium levels, and/or high potassium levels. Since Miralax pulls water from the body and into the stools, it can make cats dehydrated. It is recommended to feed wet or canned food to cats taking Miralax to help prevent dehydration.

Since Miralax speeds up how quickly things move through the intestines, other drugs and medications should not be given at the same time as Miralax. Other oral medications should be given at least one hour before Miralax administration. 

Miralax should not be given with other laxatives or stool softeners. Miralax should be used with caution with other medications that may cause electrolyte abnormalities and dehydration, such as diuretics and ACE inhibitors. 

Miralax Dosage for Cats

Cat eating wet food from a bowl with miralax powder

For cats, the recommended dose is generally ⅛ to ¼ teaspoon of powder mixed in with food twice daily. Your veterinarian will be able to give you more specific instructions based on your cat’s condition and needs. 

Make sure to speak with your veterinarian before giving your cat Miralax. The best treatment for constipation is to try to determine the underlying cause, which generally requires lab tests and X-rays at a minimum.

Do not give the labeled over-the-counter Miralax dose to cats as this is the dose for humans and is much too large for cats. 

Other Digestive Support Supplements For Cats 

If you aren’t interested in using Miralax for your cat, there are many other viable options to address occasional feline digestive upset. Cats get constipated for any number of reasons, so always check with your veterinarian first. Here are a few products to keep your kitty happy, healthy, and ‘feline’ fine. 

All featured products are chosen at the discretion of the Great Pet Care editorial team and do not reflect a direct endorsement by the author. However, Great Pet Care may make a small affiliate commission if you click through and make a purchase.

Great Pet Great Poop Digestive Support Cat Supplement

Great Poop Cat Digestive Supplement

A wise old saying goes, “An ounce of prevention is worth a pound of cure.” In a perfect world, cats poop at least once a day. The consistency of that poop is solid, but not too hard nor too soft, and not overly smelly. Great Poop for Cats gives your feline family members a healthy digestive tract so proper poop happens. It’s infused with probiotics and digestive enzymes in a chewable format your cat will devour. 


  • Tasty chicken-flavored chew means no more messing with powders or pills
  • Promotes a healthier gut for more regular pooping cycles
  • Normalizes poop consistency for easier litter box cleanup 
  • Proudly made in the USA
  • Made with natural, active ingredients including ginger root powder, pumpkin seed powder, and probiotics 
  • Helps prevent diarrhea and loose stools, constipation, and bloating 

Things to Consider

  • Check with your veterinarian before starting probiotics if your cat is very ill or has a compromised immune system.
  • For cats one year of age or older
  • Feed one to two chews daily depending on the weight of your cat

Purina FortiFlora Cat Probiotic Powder Supplement

Purina Fortiflora for Cats

Help restore your cat’s intestinal health and balance without messy liquids or hard-to-administer pills. FortiFlora for cats promotes beneficial intestinal microflora. Sprinkle one package on your feline’s food each day for cats suffering from diarrhea. Designed for cats of all ages and sizes, FortiFlora was created in collaboration with nutritionists, researchers, and veterinarians. 


  • Each sachet contains 500 million live microorganisms for more beneficial effects on your cat’s digestion and health.
  • Easy to administer packet that easily combines with kitty’s meal each day
  • Palatable taste with liver flavor as the main ingredient
  • Available in 30, 60, 90, and 180-count sizes
  • Made in the United States
  • Promotes a healthy immune system

Things to Consider

  • Follow your veterinarian’s advice when using FortiFlora
  • Use under your veterinarian’s direction if your cat requires a limited ingredient diet

Tomlyn Laxatone Hairball Remedy Gel for Cats and Kittens

Tomlyn Hairball Remedy for Cats

Some cats become constipated as a result of hairballs. TOMLYNs Laxatone gel allows ingested hair to move through the digestive tract and into your cat’s stool. Administer by placing a dollop on your cat’s nose or paws to stimulate licking. A tasty variety of flavor options ensures your cat never misses a lick. For those who prefer a chewable version, TOMLYN offers Laxatone chews for cats.


  • Oils act as gentle digestive lubricants to help move hairballs along the digestive tract
  • Can be used daily to aid in the prevention and elimination of hairballs
  • Received the National Animal Supplement Council (NASC) seal 
  • Rich in omega-3, -6, and ‘9 along with fatty acids
  • Four irresistible flavor options dispensed according to your cat’s size 
  • Available in tuna, maple, and catnip flavors

Things to Consider

  • Consult your veterinarian before giving your cat Laxatone
  • The dosage depends on the weight of your cat
  • Contains soybean oil
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