Can Rats Eat Chocolate? Is Dark, Milk & White Choc Toxic?

On the list of favorite foods of all time, chocolate probably ranks pretty high. As a Swiss, I couldn’t disagree!

But is chocolate safe to share with your pet rats?

Can chocolate be toxic to them, and in what amounts?

As is the case for other pets, the theobromine contained in chocolate can have a toxic effect on rats. However, they would need to ingest pretty hefty doses for that to become relevant. But there are other reasons why chocolate does not make the best treat for rats.

To get the rundown on chocolate for rats, just read on below.

Rats & Chocolate

Should Rats Eat Chocolate?

Chocolate is made from the seeds of the cacao tree (Theobroma cacao). As the latin name indicates, chocolate contains theobromine, which can be toxic for pets. Another toxic agent in chocolate is caffeine – the same as in coffee.

Both caffeine and theobromine are methylxanthines, substances which inhibit specific cell receptors and thus cause an increased heartrate and other cardiac problems, seizures, and many other symptoms1.

Dark Chocolate
Photo by Charisse Kenion on Unsplash

Methylxanthines are toxic to different species in different dosages – you’ve probably heard that dogs are very sensitive to chocolate toxicity; but other pets can be affected, too. This depends on different factors, such as how long the methylxanthines stay inside the body.

For humans, this time is very short, but for pets, the half-life of theobromine tends to be a lot longer2.

The lethal dose of theobromine for rats is rather high, so it’s rare for chocolate to cause serious problems for them. However, there is some research that indicates that theobromine might be harmful in lower concentrations, too – especially when fed on a regular basis.

Theobromine seems to have negative effects on the fertility of male rats, and it can cause rats to reject other foods3. There is also some evidence of damage to the kidneys and the heart4.

Long story short, a little bite of chocolate won’t harm your rat – but there are definitely better suited treat options out there. Chocolate should not be a staple of your pet rats’ diet.

How Much Chocolate Can Kill A Rat?

Pet Rat Eating Chocolate Spread
Photo by PublicDomainPictures on Pixabay

The LD50 dose of theobromine for rats is 1’265 mg/kg5.“LD50” means that this is the dosage that will kill 50% of the rats that ingest it. Obviously, harmful effects start at lower amounts than that, but the LD50 is a good measure to base calculations on.

Dark chocolate contains between 5 and 13 mg of theobromine per kg, whereas milk chocolate can contain up to 2.5 mg per kg1 . This means that an average-sized rat of 300 grams or 11 ounces would need to eat about 30 grams (1/4 cup) of dark chocolate or 150 grams (a large bar) of milk chocolate for it to be lethal. Clearly, these are not amounts that would normally be fed to a rat.

Obviously, it doesn’t take a lethal dose for your rat to feel any effects, such as tachycardia (increased heartrate). It’s therefore best to only give chocolate in very small amounts – or preferably not at all.

Do Rats Like Chocolate?

Unfortunately, rats really like chocolate. This is probably due to the high sugar and fat content, which make it a very tasty snack. Still, you should not feed them chocolate on a regular basis. A very small piece of chocolate as a special treat now and then is alright. For example, you could use it to mask the taste of a medicine your rats need to take.

Can Rats Eat White Chocolate?

White Chocolate
Photo by Syed Shameel on Flickr

White chocolate has negligible theobromine contents, so toxicity is not a concern. It is, however, high in sugar and fat and therefore not the best snack for pet rats. Overweight rats tend to have a shorter lifespan, so it’s important to watch your pet rats’ diet.

Can Rats Eat Dark Chocolate?

Since dark chocolate contains the most theobromine, it’s best to avoid it or limit its intake to a very small piece every now and then. If you want to give your rats a bit of chocolate – for example, to make it easier for them to take their medicine – milk chocolate would be a safer bet. Milk chocolate does not contain as much theobromine, but keep in mind that it is higher in sugar.

Overweight Rat Eating Chocolate and Junk Food

What Other Foods Are Toxic To Rats?

You may have found it surprising that something as common as chocolate can potentially be dangerous for your pet rats.

Other foods that are toxic to your rats include: Avocado skin and pits, the skin of citrus fruits and mangoes, and raw sweet potato. In addition, peanut butter contains fungal toxins that may be harmful to rats.

You may also wonder if you can feed your rat other pet foods such as dog food, cat food or rabbit and guinea pig food. While a small amount of these might not be harmful, it is not the ideal food for your mischief.

Before feeding your rats a new food, it’s best to take a couple of minutes to research whether it is safe and healthy for them.

To Sum Up

Chocolate contains methylxanthines (theobromine and caffeine) which are toxic to rats in high doses. Dark chocolate contains higher amounts of theobromine and should be avoided. Small amounts of milk or white chocolate are fine, but they’re not the healthiest choice of treat.


1. MsD Vet Manual. Chocolate Toxicosis in Animals 2021.

2. Finlay F, Guiton S. Chocolate poisoning. BMJ : British Medical Journal 2005;331:633-633.

3. Gans JH. Comparative toxicities of dietary caffeine and theobromine in the rat. Food Chem Toxicol 1984;22:365-369.

4. Tarka Jr SM, Morrissey RB, Apgar JL, et al. Chronic toxicity/carcinogenicity studies of cocoa powder in rats. Food and Chemical Toxicology 1991;29:7-19.

5. Owens J, Dorman D. Drug poisoning in small animals. Vet Med 1997:149-157.