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Can You Give Cats Milk of Magnesia? Is it Healthy For Cats?

David Fields
Last Updated on
by David Fields

Milk of magnesia is an effective remedy for constipation. At least, it is in humans.

So, it’s natural that when you notice your cat straining over the litter box, you consider treating them with milk of magnesia. But is that a good idea?

Is it safe to give your cats milk of magnesia? Yes. Should you do it more than once? No.

Crucially, you should only give your cat milk of magnesia after consulting your vet. They can help you evaluate the correct dose for your cat based on its weight, age, and overall health.

You can also treat feline constipation by using several home remedies. But if the problem persists, it’s time to take your cat to the vet. Your cat will thank you for it later.

Milk of Magnesia

Can Cats Have Milk of Magnesia?

Yes, you can give your cat milk of magnesia without consequences.

However, there are caveats. Firstly, you should never do this without speaking to your vet. Vets seldom recommend treating pets with human medication. That’s not because it doesn’t work but because guessing the correct dosage is challenging.

Secondly, milk of magnesia is only safe for cats in moderation. If you decide to give it to your cat, you must consider several factors that may affect the dosage size.

Consider these factors:

  • Age
  • Weight
  • Other medications
  • Chronic health conditions

How Much Milk of Magnesia Is Too Much?

Quantity of Milk of Magnesia
Quantity of Milk of Magnesia

Now we’ve established you can give milk of magnesia to cats. But how much can you safely give them?

The rule of thumb is that you should never exceed 1-3 tablespoons per five pounds of body weight a day. The medicine should always be given orally.

And if you are, quite understandably, wondering how you will get a spoon into the mouth of your recalcitrant, constipated cat, don’t worry. Tablespoons are not your only option.

While they’re effective for measuring out the milk of magnesia, you will have more luck syringing the liquid into your cat’s mouth.

As for how you catch and coral your cat, all owners have some tried and tested techniques.

Whatever your method, it never hurts to wrap the procedure up with a treat.

The other thing we want to stress is that giving your cat milk of magnesia is a one-off treatment. If it doesn’t work the first time you give it to your cat, don’t try again. The risks outweigh the potential benefits.

Instead, talk to your vet about other ways to treat feline constipation.

Can Kittens Have Milk of Magnesia?

Although you can safely feed milk of magnesia to adult cats, vets do not recommend giving it to kittens.

As discussed, measuring the correct dose is challenging when you do it for adult cats. But it’s even trickier for kittens because they grow so quickly. Their weight isn’t consistent long enough for you to correctly calculate an appropriate dose.

And if you get it wrong, you can end up with a dehydrated kitten. That means more medical expense than if you’d gone to the vet for treatment in the first place.

Consequently, if you have a kitten suffering from constipation, you should speak with your vet right away about how to proceed.

How Long Can My Cat Safely Go Without Pooping?

If you are researching milk of magnesia as a constipation cure, then you probably are also curious how long it will be before you must seek veterinary care for your cat.

Ideally, your cat poops every day. If they don’t, don’t panic. Some cats only poo every 48 hours.

Cat regularity depends on the following factors:

  • Efficacy of digestive tracts
  • Activity level
  • How much the cat eats

However, if your cat does not produce stool after 48 hours, it may have an internal blockage. Since these can quickly become severe health conditions, it’s essential to call your vet immediately.

How Do I Tell If My Cat Is Constipated? 

Constipated cat
Constipated cat

It’s one thing to give cats milk of magnesia. But how do you know they need it?

With indoor cats, routinely cleaning your cat’s litter box or boxes should be enough. However, it can be harder to judge whether or not an outdoor cat eliminates regularly.

So, how can you tell if a cat is constipated?

Some common symptoms include:

  • Nausea
  • Loss of appetite
  • Increased urination
  • Stiff when walking
  • Hiding
  • Straining over the litter box
  • Reluctance when jumping

If you still can’t tell if the cat is constipated, try palpating its abdomen.

This process may be complicated because cats are naturally protective of their bellies. It can also be challenging if you have never done this before and aren’t sure what you are looking for.

Assuming your cat lets you, gently squeeze their underbelly. A constipated cat will have a full bladder and built-up fecal matter in the colon. This should feel like a hard mass.

A tolerant cat may let you massage the area, which helps the hardened fecal matter move through the colon. But if you aren’t sure what you feel and want an expert opinion, call your vet.

Alternatives To Giving Cats Milk of Magnesia

While giving cats milk of magnesia is safe as long as your vet agrees to the treatment, not everyone feels comfortable administering it.

So, what else can you do to combat feline constipation at home?

Olive Oil

One of the easiest home treatments for constipated cats is to give them a spoonful of olive oil. It’s an effective laxative and won’t negatively affect your cat.

However, a little olive oil goes a long way. Too much could give your cat diarrhea and cause dehydration.

One of the best ways to give your cat olive oil is to drizzle a tablespoon over a modest portion of tuna.

Alternatively, if you buy tinned tuna stored in oil, you can eschew the olive oil. Simply spoon out the tuna, taking care to include some oil from the tin.


Another effective milk of magnesia alternative for cats is pumpkin. Many pet stores carry pumpkin-based supplements for your cat.

But a tin of store-bought pumpkin is equally effective. The fiber helps promote healthy stool and keep your cat’s bowels moving.


If you want a quick and easy laxative that cats will love, forget milk of magnesia. It’s well-documented that cats love milk.

What most people don’t realize is that cats are lactose intolerant. That makes milk extremely effective in helping loosen stool.

However, like olive oil, your cat should only have milk in moderation. Too much causes severe diarrhea and vomiting. This is particularly important if you are treating a kitten since dehydration can be fatal.

But for a constipation cure your cat won’t fight you over, a saucer of milk is hard to beat.

What type of milk should you give your cat (in moderation)?:

Vet Approved Remedies

Finally, many veterinary-approved laxatives are designed to help your cat eliminate stool and hairballs.

These differ from practice to practice but are always available over the counter.

Some, like Metamucil, can be sprinkled on your cat’s food. Others, like Lax ‘Aire, are a paste. Theoretically, all should be appealing to your cat. But fussy cats may need a paste-based supplement to be rubbed on their paws. This encourages them to wash it off, thereby ingesting it.

Always follow the directions on the product you choose. Many supplements should only be used for three to five days. While there may be exceptions for long-haired cats, who are prone to hairballs, always ask your vet before continuing treatment beyond the recommended guideline.

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About David Fields
David Fields
David Fields is a long-time animal lover and has been blessed to share his life with many companions. A short list includes ragdoll cats, siberian husky and greyhound dogs, an African Grey parrot, many fish of all sorts, and a pandemonium of parakeet. He writes most of the articles on iPetCompanion and is regularly featured on other popular websites on the Internet.
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