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Known Side Effects of L-Theanine for Dogs

L-Theanine is a phyto-amino acid known for its calming properties. It is present in Camellia sinensis, the plant used to make green tea and black tea, as well as in certain mushrooms. As a supplement, L-Theanine can help manage stress and anxiety in dogs. But are there known side effects of L-Theanine for dogs? Read on to learn more about this nutraceutical and other ways to keep your canine companion calm. 

Known Side Effects of L-Theanine for Dogs

What is L-Theanine?

Green tea is known as a calming drink, and it owes this effect to the amino acid, L-Theanine. It works by influencing the function of dopamine — a neurotransmitter in the brain, usually referred to as the feel-good neurotransmitter because it produces feelings of pleasure and satisfaction, such as when we eat a food we like or during sex. 

Studies that have looked at L-Theanine have established that this amino acid can help stabilize mood with little risk for adverse reactions and toxicity. It promotes relaxation without causing drowsiness. 

Results from a small study involving storm-sensitive dogs suggests that L-Theanine can help ease this common dog reaction to storms. The study’s findings revealed that there is less drooling, panting, pacing, hiding, and following people around; the dogs’ overall response to the stressor can be diminished by giving them L-Theanine. 

Known Side Effects of L-Theanine for Dogs

How does L-Theanine work in dogs?

Dogs may experience stress or anxiety in certain situations, such as during thunderstorms, fireworks, or car rides, or when they are separated from their human companion or placed in an unfamiliar environment. 

Symptoms of Stress and Anxiety in Dogs

When exposed to a stressor, your dog may exhibit any of the following behaviors:

  • Frequent panting
  • Inability to relax or rest
  • Constant pacing
  • Constant or out-of-the-ordinary vocalization
  • Aversion to strangers
  • Varying levels of reactivity or aggression

Avoiding exposure of your pet to his known stressors is not always possible. And when your pet pal becomes stressed or anxious, managing his behavior is oftentimes difficult. Normally, a dog only calms down once the stressor is no longer present, e.g., the thunderstorm has subsided or their human has come home. 

Available as a pet supplement or a treat, L-Theanine is a natural anti-anxiety solution that should be given before the onset of stress, such as 15-20 minutes before a car ride or the start of fireworks. 

Known Side Effects of L-Theanine for Dogs


Always consult a vet before giving your canine pal any new drug or supplement. Dosing recommendations will also be found on the product information/insert. The general dosage recommendations for L-Theanine are based on a dog’s weight:

  • 100 mg for 10-20 lbs
  • 200 mg for 21-40 lbs
  • 300 mg for 41-60 lbs
  • 400 mg for 61-80 lbs
  • 500 mg for 81 lbs and up

If subsequent doses are needed, they should be given at least every six hours. Because every dog responds differently to L-Theanine, it’s best to start your dog on the lowest recommended dosage for his weight group. If you do not see the desired result, gradually increase the dose after 6 hours, or the next time you need to preempt his anxiety/stress. Continue with the gradual adjustments until your dog experiences the calming effect, but do not go beyond the maximum recommended dosage for his weight. 

Known side effects of L-Theanine for dogs

It’s important to always carefully follow dosage recommendations when giving your best bud medicine or supplements. So far, there are no known adverse reactions to or risk of toxicity from L-Theanine. It is generally considered to be safe, but caution should still be practiced when giving it to a pregnant or nursing dog; get your vet’s go ahead before starting any home treatments for a pregnant/nursing pet. 

Due to its calming properties, L-Theanine may lower blood pressure, so it might not be advisable to give L-Theanine together with medications that lower blood pressure or to a dog with hypotension. 

Additionally, always check the product information for other ingredients present. And carefully read the product’s precaution section. For Anxitane, for example, which is a popular L-Theanine supplement for dogs, the product insert cautions against giving it to dogs with severe phobias, separation anxiety, or aggression. 

Known Side Effects of L-Theanine for Dogs

Alternative remedies for stress and anxiety in dogs

Another option you may want to try is CBD oil for pets. Keep in mind that you should only use CBD oil that has been specifically manufactured for pets, as this will contain the appropriate potency. CBD oil for animals is also derived from hemp to ensure that it contains less than 0.3% THC — the psychoactive compound in marijuana which is toxic to dogs and other animals. 

Anecdotal data and early clinical findings have shown that CBD oil’s calming effect on humans may also be experienced by dogs. In fact, CBD products for pets are now widely available; but it’s always a good idea to seek a vet’s advice first.