L-theanine (found in Composure and Anxitane) is a type of amino acid with some evidence to show it is effective at reducing anxiety in dogs. Because of its safety, and the low risk of side effects, it is a popular remedy for owners who don’t want to give their dog medicines like Xanax. It is thought to increase levels of dopamine and GABA in the brain, though there is differing opinions on how the substance affects serotonin levels. These chemicals play a role in mood, and can affect how anxious a dog feels.

Composure contains an additional two ingredients to help with anxiety: C3 (Colostrum Calming Complex), and Thiamine (commonly known as vitamin B1). The L-theanine in Composure is a branded form known as “Suntheanine,” which is a very pure form of the substance. Anxitane also uses “Suntheanine.”

Recommended Dosage

Note: Follow the instructions contained on the product’s label and package insert, and check with your vet before use.

The dosage will depend on the product you are using. Dosing information for both Anxitane and Composure can be found below. Dosing information should also be included on the package insert.



Weight of Dog

Anxitane S

Anxitane M & L

Under 22 lbs½ tablet twice daily
22 – 55 lbs½ tablet twice daily
Over 55 lbs1 tablet twice daily

The insert for Anxitane recommends stopping use if symptoms do not improve after 30 days.



Weight of Dog

Composure Small Canine Formula Tablets per Day

Composure Canine Formula Tablets per Day

Under 26 lbs1
26 – 50.9 lbs1
51 – 100 lbs2
Over 100 lbs3

The manufacturer states that it is safe to double or even triple the above dosage in times of stress.

Avoid using these products with D-theanine, or D,L-theanine, as these substances can reduce the absorption of L-theanine.

Example: A dog weighing 30 pounds could be given 1 “Composure Canine Formula” tablet per day, or up to 3 times daily when needed.

Is It Safe?

L-theanine is considered to be quite safe, and is not expected to cause unwanted effects. It is probably safe for pregnant or nursing dogs, but caution should be practiced in these cases. L-theanine may also reduce blood pressure, so it might not be safe to give with medicines that lower blood pressure, or to dogs who suffer with hypotension.

You should also be careful of other ingredients packaged into the product. In cases of overdose, though L-theanine itself seems to be unlikely to cause harm, these extra ingredients may pose a risk.

Anxitane’s insert states that it is not intended for use in dogs with severe phobias, separation anxiety, or a history of aggression.

Safety Guidelines

The following guidelines will help you to safely use products containing L-theanine:

  • Talk to the vet before use
  • Check the product label and insert carefully for instructions
  • Check the product label for extra active ingredients that could be harmful for your dog
  • Do not give with blood pressure medicines without approval from your vet

Stop use if your dog’s symptoms worsen.

What Is It Used For?

L-theanine is used to help reduce anxiety in dogs. A study on 5 beagles showed that beagles treated with L-theanine interacted with humans more than the placebo group, and other studies have shown evidence for its effectiveness in other animals such as cats.

Side Effects

Although adverse effects are not expected, the following may occur:

  • Hypotension

The risk is increased in dogs with hypotension or when L-theanine is given with drugs which reduce blood pressure.


L-theanine appeared to cause no adverse effects in rats, even at a dosage of 4 grams/kg per day.


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