L-Theanine

What is L-theanine?

L-theanine (ANXITANE®) is a nutritional supplement used to treat anxiety in dogs and cats. L-theanine is an amino acid naturally found in green tea leaves. 

The U.S. Food and Drug Administration (FDA) does not review non-drug health supplements (e.g., herbals, nutraceuticals, shampoos, and other supplements) for safety or effectiveness before they are sold to the public. Manufacturers of non-drug health supplements must ensure their supplements are safe and labeled accurately. The FDA requires that these non-pharmaceuticals contain a disclaimer that says, “This supplement is not intended to diagnose, treat, cure or prevent any disease.” Health Canada licenses “veterinary health supplements” after reviewing safety, efficacy, and manufacturing information provided by the manufacturer. These supplements are not tested by Health Canada.

Your veterinarian is the best source of information about the safety of non-drug health supplements in pets. Just because a supplement is natural does not mean it is safe. All medicines and medicinal plants are potentially toxic if used inappropriately or given at high doses. Supplements can also have side effects, like pharmaceuticals. Few supplements and herbs have been subjected to rigorous scientific trials to determine their efficacy. 

Although the information in this handout may be helpful, it may also be incomplete and may not represent the full range of effects the supplement could have on your pet.

How do I give my pet L-theanine?

• L-theanine is given orally (by mouth) and comes as a palatable, chewable tablet. 
• Tablets may be given with or without food. 
• Follow your veterinarian’s directions; use supplements according to their label.
• Ideally, give this supplement at the same time each day.
• Always ensure access to fresh, clean drinking water.
• Wash hands after handling,
• Do not handle if you have a known sensitivity to this supplement.

L-theanine may take several days to take effect, and improvement in clinical signs may not be noted outwardly.

What if I miss giving my pet the supplement?

If you miss a dose, give it as soon as you remember. However, if it is almost time for the next scheduled dose, skip the missed dose and resume the regular dosing schedule. Do not give the pet two doses at once. 

Are there any potential side effects from L-theanine?

• Although not documented in L-theanine, oral supplements can cause mild gastrointestinal symptoms such as loose stools, flatulence and stomach upset. If this occurs, contact your veterinarian.
• Sensitivities can develop over time with repeated exposure. Your pet may have no reaction after the first few doses but may develop a sensitivity later. It is important to watch for signs of an allergic reaction over the entire course of treatment.
• Other side effects may occur. If you notice anything unusual, contact your veterinarian immediately.

This short-acting drug/supplement should stop working within 24 hours, although effects can be longer in pets with liver or kidney disease.

Are there any risk factors for this supplement?

DO NOT USE L-theanine in:

• Pets who are allergic to it or to any of the ingredients in the supplement.
• Animals with severe phobias or separation anxiety.
• Animals with a known history of aggression.

Contact your veterinarian if your animal's condition does not improve within 60 days or worsens despite this treatment. 

Are there any drug interactions I should be aware of?

Certain medications should be used WITH CAUTION when given with L-theanine, including:

• Antihypertensive agents: L-theanine can potentially reduce blood pressure and cause additive effects.
• D-theanine; D,L-theanine: Can reduce the absorption of L-theanine.

Be sure to tell your veterinarian about any medications (including vitamins, supplements or herbal therapies) that your pet is taking before starting any treatment.

Is any monitoring needed with this supplement?

• At home, monitor for any abnormal changes. If these occur, discontinue the supplement and contact your veterinarian.
• Your veterinarian will let you know when they want to reassess your pet to ensure the supplement is working and not causing side effects. 

How do I store L-theanine?

• Store in a cool, dry area in a tightly sealed container to prevent accidental ingestion.
• Keep tablets in original blister pack until used.
• Keep out of the reach of children.

What should I do in case of emergency?

• If you suspect an overdose or an adverse reaction to the supplement/treatment, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility. Be prepared to provide information about the product and your pet's weight and symptoms.
• Adverse effects should also be reported to the FDA or Health Canada.