LEGO and pets are two of the most common additions to a household, so it is normal to wonder if LEGO is safe for pets. In this post, I am going to share the research I have done to find out about that.

So, is LEGO safe for pets? With a few exceptions, LEGO is not harmful to pets, but it can’t be classified as a safe toy either. So, the best strategy is to keep LEGO away from pets and, because the risk of harm is low, the chances of something bad happening with the occasional interaction becomes minimal.

The answer can vary a lot depending on the type of pet you have, so I have divided this post into different sections, each for a different type of pet.

Is LEGO safe for fish?

We have dedicated a whole article to answer this topic since it is a very common concern. In this case, LEGO is, as long as you use certain precautions, safe to use in aquariums. LEGO is made from ABS plastic, which is a very stable plastic that does not release chemicals to the water.

The following are the precautions you should follow in order to make LEGO safe for fish.

  • Ensure there are no floating LEGO pieces
  • Ensure that there are no hazardous materials attached to your LEGO
  • Ensure that there are no pieces that can directly damage your fish
  • Ensure that the pieces are waterproof and easy to clean

Ensure there are no floating LEGO pieces

Floating pieces can be a danger to your fish because they could confuse them with food or get harmed by the edges. So, the best strategy here is to fix the pieces in a way that they will not float. There are four main systems you can use.

  1. LEGO boat weights: These are modified LEGO pieces with added weight that will make your LEGO construction heavy enough so that it will not float. Our favorite option
  2. Fill your LEGO with sand or stones: You can also extra weight by filling your LEGO with sand or stones or any other heavy material. The risk with this option is that this material could scratch and damage your LEGO.
  3. Glue your LEGO to the aquarium or to other decoration elements: You can simply glue your LEGO to the aquarium or to other decoration elements. Gluing it to the aquarium will make the maintenance more difficult, whereas gluing it to other decoration elements reduces the flexibility you have in where and how you want to place your LEGO. In either case, there is a risk of damage when you want to remove the LEGO from the aquarium. Also, make sure the glue you are using is non-toxic and can be safely used in aquariums.
  4. Anchor your LEGO: You can anchor your LEGO instead of gluing it. This will make it easier when you want to take out the LEGO from the aquarium, but the process of fixing it is trickier, and, if not done correctly, your LEGO could detach and float.

Ensure that there are no hazardous materials attached to your LEGO

LEGO itself is not hazardous to your fish but, if you have used your LEGO for a long time, some other materials may have attached to it that could potentially be dangerous. So, before putting your LEGO inside the aquarium, it is necessary to sanitize it properly.

The best way is to do it by hand, using water colder than 104°F / 40°C, and mild detergent. If you want to know a bit more about this process or other alternatives that you could also consider, be sure to check our post “This Is The Best Way To Clean LEGO”, where we talk about this in a lot of detail.

Ensure that there are no pieces that can directly damage your fish

Another risk for fish are pieces that could directly damage them. The main risks here are pointy objects or hard edges that could damage the not-so-thick fish skin. Minifigs’ weapons are one of the main sources of pointy objects, so you might want to keep an eye on that.

Ensure that the pieces are waterproof and easy to clean

This last tip is more for your LEGO than for your fish, but it could also be a danger to the latter. Make sure that anything you are placing inside your aquarium is waterproof and easy to clean. Algae will eventually take over your LEGO so you want to make sure that whatever you are putting inside there can eventually be cleaned.

As for waterproof pieces, do not put any electronic parts such as motors, sensors, lights, and battery boxes. They will break and they could be a hazard to the fish as well.

If you want to learn a bit more about this and other extra precautions you can take if you want to make LEGO safe for fish, you can check our post “Fish Aquariums And LEGO – Is LEGO Safe For Your Fish”.

Is LEGO safe for cats?

The next pet on our list is cats. For cats, the problem is quite different than it is for fish. In this case, the danger comes from chewing and potentially swallowing LEGO pieces.

As far as chewing is concerned, the main problem here seems to be for your LEGO and not for your cats. Cats will chew and chew until your beloved LEGO pieces are destroyed. However, ABS plastic is very stable and does not release chemicals, so this should not be a health hazard for your cat.

Swallowing seems to be not so common for cats. However, when it happens, because of their size, a visit to the vet might be required in order to get the piece out. Be sure to consult a veterinary straight away if your cat has swallowed a piece of LEGO for advice on how to proceed.

If your cat is chewing or swallowing LEGO pieces, this is what you can do to avoid it.

Store all your finished LEGO sets in a display case/cabinet

If your cats are going after your finished LEGO sets (the rubber bands in the sets seem to be a favorite), one of the best options is to store all your finished LEGO sets in a display case or cabinet. This way, you will not only keep your cat away from the LEGO set, but you will also keep the dust away, so you will not have to clean it so often.

Store all your finished LEGO in a separate room where the cat does not have access

Another option is to have your LEGO in a separate room. Somewhere where the cat cannot enter. This could be a LEGO room on its own if you have a lot of LEGOS or the bedrooms, or an office.

The downside to this is that, because they will be in a separate room, you will not be able to show them or see them as easily.

Spray your finished LEGO with a repellent spray

The third option for your finished LEGO is to spray it with a cat repellent spray. These are sprays that have a smell that cats don’t like, so they stay away from it. Keep in mind that, if you are not careful about spraying it, your cat might not even want to stay in that room. But, used correctly, it can help with keeping your cat away from your finished LEGO sets.

Store all the loose pieces safely in a compartment the cat cannot access

The biggest risk for cats is swallowing on loose pieces that are small enough to fit in their mouth but too big to be swallowed or disposed of through the stool. In this case, surgery may be required in order to remove the object.

To avoid that, make sure you don’t leave any loose pieces around after you finish playing. Store them safely in a compartment that the cat cannot access.

Don’t allow the cat to go in the room where you play with your LEGO

If storing all your loose pieces is not an option, an alternative is to play in a room where your cat cannot enter. For example, you could have a gaming or LEGO room where you don’t let your cat enter.

This way, you don’t need to worry about leaving loose pieces around because your cat will never come in contact with them.

Is LEGO safe for dogs?

Dogs and cats are a bit different as far as LEGO is concerned. For example, dogs tend to swallow LEGO pieces much more often than cats do. Also, the chewing in dogs is not so common and it usually happens only when they are puppies. Lastly, dogs are easier to train, so the strategies to stop them from messing around with your LEGO are different.

Dogs that are big will usually not have big problems when swallowing the LEGO pieces because their body is big enough to deal with them With smaller dogs, however, there is a risk of the pieces getting stuck in the body. If that happens, surgery might be needed to remove them.

Train your dog not to chew on your finished LEGO sets

Dogs are much easier to train than cats are, so the first strategy you should consider is to train your dog not to chew on your LEGO. This will happen when they are puppies since it is the time that the training should start but it is also the time where they chew more often. For training resources, you can start here, or here.

In the weeks or months where you are training your dog not to chew on your LEGO, it could be a good strategy to have them on a leash all the time when they are with you, so they are supervised. And when you cannot supervise them, have them in a specific room that has been made chewing-proof.

Alternatively, follow the same steps explained in the section for cats

If the above is not desirable or possible, the steps that are explained in the section for cats are also applicable here. However, dogs do not climb on shelves as cats do, so your biggest problem will be with pieces that are near the floor, not high on shelves.

So, from the advice that we gave before, the most important pieces of advice to remember is to not leave your LEGO pieces around if you are not playing with them or if you want to leave them around, to have them in a room where your dog is not allowed.

Is LEGO safe for hamsters?

Dogs and cats are the most common pets that people have, but rodents are also a common pet to have. Out of that family, both hamsters and guinea pigs are the most common. Regarding hamsters, LEGO is a very unsafe element to have around for these little rodents. There are three main causes for concern here.

  1. Chewing / swallowing the plastic
  2. Getting their claws caught in any gaps
  3. Walking on a bumpy or hard surface

The only exception is to use LEGO only as a playground and always under your supervision so you could act if you see them starting to chew it. You can check this very funny video where somebody built a maze made of LEGO for their hamster.

Chewing / swallowing the plastic

The first concern for hamsters is the same as for cats and dogs, which is chewing and swallowing. However, in hamsters, this is more dangerous. Their body is much smaller and delicate, so you need to be extra careful with that.

Moreover, hamsters are much more prone to chewing than cats or dogs are. Therefore, they will chew on anything inside their cage, no matter what it is. For example, you need to be very careful not to place any metal pieces in their cages because otherwise they will start chewing them and they could die of metal poisoning.

Getting their claws caught in any gaps

Hamsters are very small pets with equally small claws. Depending on which type of LEGO toy you give them, their claws could easily get caught in the gaps between the pieces, which could damage the claws.

Walking on a bumpy or hard surface

The last concern is the fact that LEGO tends to have a bumpy finish and it is also a hard surface. If your hamster walks a lot on the LEGO you have put there, that could cause bumblefoot.

Bumblefoot is basically an inflammation of the feet and, if not treated in time, amputation might be required.

Is LEGO safe for guinea pigs?

Guinea pigs are bigger than hamsters so the dangers that we discussed in the previous section are not so big. However, they still apply and therefore we don’t think that LEGO is safe for guinea pigs. It could potentially be used as a playing ground as it happens with the hamsters and the risk will be lower in this case, but in any case, you should keep an eye on them at all times.

This video shows two guinea pigs interacting with a LEGO “labyrinth”.

Is LEGO safe for parrots?

The last pet we want to talk about is parrots. Parrots, like hamsters and guinea pigs, like to chew everything that is in sight, so having LEGO around can be a very dangerous idea. Also if their claws get trapped, the result can be surprisingly dangerous. Let’s see each of these concerns.

Chewing / swallowing the plastic

The first concern for parrots is the same as for all the other animals, that are chewing and swallowing LEGO pieces. Parrots are quite clever so swallowing is not the most likely outcome. However, they like chewing whatever is around and, if they manage to break a LEGO piece and that forms splinters, that could create damage to your parrot.

However, if you only give LEGO to them for playing and you are always keeping an eye on them while they are interacting with the LEGO, it can be an interesting change for the parrot.

Getting their claws caught in any gaps

The second concern is getting their claws caught in any gaps. As it happens with the hamsters and the guinea pigs, the claws of the parrots are small enough for them to get trapped in gaps that can be present in LEGO sets. And, according to this video, parrots would actually chew their own feet out if they get a claw stuck somewhere. Imagine coming back home and finding that! Not a scene you want to have.

But, if you are present and actively keeping an eye on the parrot while it interacts with the LEGO pieces, you can step in and help if needed.

Final words

And with this, we have arrived at the end of this post. In this post, we have talked about how safe LEGO is for pets. We have talked about fish, cats, dogs, hamsters, guinea pigs, and parrots. We have learned that, in most circumstances, you need to be careful with letting your pets interact with your LEGO, mostly because of the risk of chewing or swallowing.

Learn More

If you are interested, here is a link to the entire Lego section found on Amazon.