If you have an anxious cat, or one prone to stress, you will of course want to do everything in your power to make them feel better. Anxiety in cats can manifest in a variety of ways, from the subtle to the more obvious, and getting to the bottom of the problem can be difficult. Many concerned cat owners turn to calming supplements to help their feline friend – but do they actually work? Let’s take a look. 

Is my cat stressed?

It can be difficult to tell whether your cat is stressed. Cats are good at concealing pain and stress; a trait that served them well in the wild before they were domesticated. You may notice that your cat’s behaviour towards you has changed, or perhaps they have started being ‘naughty’ at home. 

Here are some common signs of anxiety in cats.

  • Hiding away
  • Change to appetite and thirst
  • Becoming less tolerant to people, less affectionate or even aggressive
  • Scratching furniture
  • Toileting in the house, outside the litter tray
  • Excessive vocalisation
  • Tense, crouched postures
  • Vomiting or diarrhoea
  • Excessive grooming

The Cats Protection 2021 CATS report found that a concerning 45% of cats in the UK are showing at least one symptom of stress. Given that there are over 10 million pet cats in the UK, that’s sadly a lot of anxious cats. 

What are calming supplements?

There is a huge range of products aimed at calming cats. The supplement market, unlike medicines, is not well regulated. Supplements do not have to pass the same stringent tests that medical drugs do to prove their safety and effectiveness. The quality and efficacy of these products therefore varies hugely. 

Calming supplements for cats contain varying ingredients: L-tryptophan, GABA, alpha-casozepine, B vitamins and more. But do they actually work? The evidence behind supplements is often confusing, as there is no requirement for robust studies to be done before the product is sold. 

Let’s take a look at some of these ingredients, how they might work, and the evidence behind their use.


Tryptophan is an essential amino acid which is involved in the production of serotonin. Serotonin is a neurotransmitter important in the regulation of mood and sleep. Supplementing tryptophan is therefore suggested to improve wellbeing by elevating mood and promoting good sleep quality. 

In cats, there is mixed evidence as to how well this theory works out in practice. One study found that a diet supplemented with L-tryptophan (together with another anti-anxiety agent) led to a reduced anxiety response in cats placed into an unfamiliar environment. However, it did nothing for cats placed with an unfamiliar person. 

Another study found that a diet supplemented with L-tryptophan (again, with another calming supplement) found reductions in the amount of cortisol (a stress hormone) in the cats’ urine after eight weeks. However, levels of this stress marker in the blood were not affected when tested after a stressful event. 

In more positive news, cats who suffer from recurrent cystitis, a disease that is highly linked to stress in cats, had markedly less recurrence of the problem when fed a diet which contains L-tryptophan, as this small study shows.

In all these studies, the diet or supplement also contained another common calming agent for cats: alpha-casozepine. It is therefore impossible to tell the absolute role that L-tryptophan has, and the evidence appears very mixed. More studies are desperately needed to follow up some of these small promising signs. 


This is a natural supplement derived from a milk protein called casein. It is thought to contain a protein molecule that plays a role in sending relaxing and calming messages to infants after they take in a milk feed. 

Alpha-casozepine is included in the three studies mentioned above for L-tryptophan, as the two are often combined. It is therefore difficult to tell which, if any, of these products may be having a positive effect. 

One study using alpha-casozepine alone on cats visiting a veterinary surgery found that its use resulted in a small, but insignificant reduction in the amount of stress hormone in the faeces of supplemented cats. But the only physical sign of stress reduced was a lack of sweaty paws in the supplemented group. There was no change to other signs of stress such as respiratory rate and pupil size. However, encouragingly, another study showed a positive effect of a 56 day trial of alpha-casozepine on various anxiety disorders in cats. 

Again, the evidence is mixed, and it is recommended that more large, robust studies are performed to gain a more definitive opinion of the efficacy of these products. 

Synthetic pheromones

Pheromones are a type of scent communication widely used by cats. Released from specialised glands, there are different types of pheromones that give different messages. They can signal warnings or territory markers, they can indicate safety and comfort, and they can give messages about other nearby cats. 

These pheromones can now be made synthetically, and released in diffusers or sprays. Their aim is to send signals to our cats that they are safe and comforted, to relieve anxiety in the home, the car, or at stressful places such as a cattery or the vets. This study found that synthetic pheromone sprays reduced stress at the vets. There have been other studies which have found that pheromone therapy can reduce urine spraying and also reduce aggression in multi cat households.

Of all the supplements, the synthetic feline pheromones seem to have the most solid evidence base.


GABA (Gamma-aminobutyric acid) is an important neurotransmitter in the brain, and its role in the human brain includes balancing out excitatory neurotransmitters, therefore having a ‘calming’ effect. It is therefore possible that it might be helpful in human anxiety disorders. There is currently little evidence about its use in cats, and more research is needed. 

B Vitamins

A balanced diet is beneficial in many aspects of health, and there has been much research into the role that various vitamins and minerals play in our wellbeing. B vitamins are important in brain function and reducing excitability. In human studies, high doses of B vitamins can reduce stress and improve mood. The evidence is again not really there yet for cats, but there have been studies showing some improvement in cats with cognitive decline when supplemented. Cats appear more sensitive to B vitamin deficiencies, so this may be worth investigating in cats with anxiety.

Herbal supplements

There are many herbal remedies marketed as being good for reducing stress and anxiety and potentiating a calmer mind. Many plants contain active chemical compounds, and indeed, many of our modern medicines come from a plant background initially, so there may well be truth in this. Common herbal remedies include valerian, lemon balm and Passiflora incarnata

Yet again, the evidence is somewhat lacking. Lemon balm has some interesting evidence as an anti-anxiety supplement in humans, as does Passiflora incarnata, but as yet no solid clinical trials for cats. Valerian is commonly touted as an excellent calming herb for cats, but although cats have been found to be stimulated by valerian, there is no evidence that it reduces anxiety or stress. 

What does this all mean?

Confused? Understandably. There are a whole host of calming supplements available for cats, each with a different combination of ingredients, many of which we have no idea whether they work! There are some definite possibilities for some of the supplements to have a positive effect, and growing evidence in the human population which hopefully will lead to further research in the veterinary fields. 

Behavioural problems are often complex, and benefit from both medication and behavioural modification, such as changes to the environment and our interactions with our pets. If you are concerned that your cat is anxious or stressed, a veterinary behaviourist will be able to suggest a treatment plan which will support both you and your pet, and will be happy to discuss calming supplements as a part of that multimodal plan.

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