Supplements

The Complete Guide to Calming Ingredients for Pets

Not all calming ingredients are created equal. Here's what the evidence says about each one.

Updated February 28, 2026

Why ingredients matter more than brand names

Walk into any pet store and you'll find dozens of calming products. Chews, drops, powders, treats. They all promise a calmer pet. But the real question isn't which brand to buy — it's which ingredients actually do something.

Different calming ingredients work through different pathways in the brain and nervous system. Some affect serotonin. Others target GABA receptors. A few work on the endocannabinoid system. Understanding these differences helps you pick the right ingredient for your pet's specific type of anxiety.

L-theanine

What it is

L-theanine is an amino acid found naturally in green tea. It's been studied extensively in humans and has a growing body of veterinary research supporting its calming effects in dogs and cats.

How it works

L-theanine promotes the production of alpha brain waves — the same pattern associated with relaxed alertness in humans. It also increases GABA, serotonin, and dopamine levels in the brain. [Kimura et al., 2007 — Nutritional Neuroscience]

What the research says

A study published in the Journal of Veterinary Behavior found that dogs given L-theanine showed significantly reduced storm anxiety and general fearfulness compared to a placebo group. [Araujo et al., 2010 — J Vet Behavior] Another study found it helped cats adapt more quickly to unfamiliar environments.

Our take

L-theanine is one of the best-supported calming ingredients for pets. It doesn't cause drowsiness, it has a strong safety record, and it works relatively quickly. It's especially good for situational anxiety — like storms, travel, or vet visits.

Melatonin

What it is

Melatonin is a hormone that your pet's body already produces naturally. It helps regulate the sleep-wake cycle and plays a role in seasonal behavior patterns.

How it works

Melatonin binds to specific receptors in the brain that promote drowsiness and relaxation. It also has mild anti-anxiety properties, though it's primarily a sleep regulator rather than a direct calming agent. [Zisapel, 2018 — British Journal of Pharmacology]

What the research says

Veterinary studies on melatonin and anxiety are limited, but clinical use is widespread. Many veterinarians recommend melatonin for noise phobias, separation anxiety at bedtime, and travel-related stress. It's considered safe for most dogs when properly dosed. [Plumb's Veterinary Drug Handbook]

Our take

Melatonin is best for anxiety that involves sleeplessness or nighttime restlessness. It's gentle, affordable, and widely available. But it's not the strongest choice for daytime anxiety or high-intensity fear responses. Check out our full melatonin guide for dosing details.

Chamomile

What it is

Chamomile (usually German chamomile, Matricaria recutita) is one of the oldest herbal remedies in the world. It's been used for centuries in human and animal medicine for its gentle calming properties.

How it works

Chamomile contains apigenin, a flavonoid that binds to GABA receptors in the brain — the same receptors targeted by prescription anti-anxiety drugs like benzodiazepines, though much more gently. [Srivastava et al., 2010 — Molecular Medicine Reports]

What the research says

Most chamomile research has been done in humans, where it shows modest but real anti-anxiety effects. Direct veterinary studies are limited. However, chamomile is generally recognized as safe for dogs and appears in many veterinary-formulated calming products.

Our take

Chamomile is a gentle ingredient that's unlikely to cause harm. It's a reasonable addition to a calming blend, but probably not strong enough on its own for moderate to severe anxiety. Think of it as a supporting player, not a lead.

Valerian root

What it is

Valerian (Valeriana officinalis) is a flowering plant whose root has been used for centuries as a natural sedative and anxiety remedy.

How it works

Valerian appears to increase GABA levels in the brain, which has a calming and mildly sedative effect. It may also reduce the breakdown of GABA, helping it stay active longer. [Bent et al., 2006 — American Journal of Medicine]

What the research says

Valerian has been studied in humans for sleep and anxiety with mixed results. Veterinary-specific studies are scarce. Some veterinarians use it in multi-ingredient calming formulations, and anecdotal reports from pet owners are generally positive.

Our take

Valerian can be helpful, but it has a strong smell that some pets dislike, and the evidence is weaker than for L-theanine or CBD. It may work better in combination with other ingredients. One caution: valerian can interact with sedative medications, so talk to your vet if your pet takes anything for anxiety.

Passionflower

What it is

Passionflower (Passiflora incarnata) is a tropical flowering vine with a long history of use in herbal medicine for anxiety and insomnia.

How it works

Like valerian, passionflower appears to boost GABA activity in the brain. Some research suggests it may also affect serotonin levels. [Appel et al., 2011 — Phytotherapy Research]

What the research says

One human clinical trial found passionflower comparable to the prescription drug oxazepam for generalized anxiety, with fewer side effects. [Akhondzadeh et al., 2001 — J Clinical Pharmacy & Therapeutics] Veterinary-specific data is minimal, but passionflower is showing up in more veterinary calming products.

Our take

Passionflower is an interesting ingredient with early promise. It's worth considering as part of a blend, but we'd like to see more pet-specific research before calling it a standout.

CBD (cannabidiol)

What it is

CBD is a non-psychoactive compound from the hemp plant that interacts with your pet's endocannabinoid system.

How it works

CBD modulates the endocannabinoid system — a network of receptors that regulate mood, pain, inflammation, and stress response. Rather than directly activating these receptors, CBD helps the body use its own endocannabinoids more efficiently. [Silver, 2019 — JAVMA]

What the research says

CBD has more veterinary research supporting its use than most other natural calming ingredients. Studies have shown benefits for pain, seizures, and stress-related behaviors in dogs. For a complete breakdown, see our full CBD guide.

Our take

CBD has the most compelling evidence of any ingredient on this list for anxiety specifically. The main challenge is product quality — the market is poorly regulated, so choosing a reputable brand matters enormously.

Ingredients to approach with caution

A few things to watch out for when shopping for calming supplements:

• Kava kava. Effective in humans, but potentially liver-toxic in dogs. Most veterinary experts advise against it.
• St. John's Wort. Has dangerous interactions with many medications and can cause photosensitivity. Not recommended for pets without veterinary supervision.
• Proprietary blends that don't list individual ingredient amounts. If a company won't tell you how much of each ingredient is in the product, you can't evaluate whether the dose is effective.
• Xylitol in chewable supplements. This artificial sweetener is extremely toxic to dogs, even in small amounts.

Putting it together

If your pet has mild, occasional anxiety, an L-theanine or chamomile-based chew may be enough. For more persistent anxiety, CBD offers stronger evidence. For sleep-related issues, melatonin is a solid choice.

Many of the best calming products combine two or three of these ingredients — and that can make sense, since they work through different pathways. Just make sure each ingredient is present at an effective dose, not just sprinkled in for label appeal.