Is Melatonin Good For Cats In Heat?

What is melatonin and how does it work?

Melatonin is a hormone produced by the pineal gland in the brain that helps regulate sleep and wake cycles. It is often referred to as the “sleep hormone” since it is associated with control of the body’s circadian rhythm (internal 24-hour clock). Melatonin levels naturally rise in the evening and fall in the morning, promoting sleepiness at night and wakefulness during the day.

Melatonin acts on melatonin receptors in the brain to induce drowsiness, reduce core body temperature, and regulate the release of other hormones related to the sleep cycle. It helps synchronize circadian rhythms with the earth’s natural light-dark cycle, allowing the body to determine when to be awake or asleep.

In addition to sleep regulation, melatonin has various other functions in the body. It acts as a powerful antioxidant, boosts immune function, and helps control inflammation. Melatonin also plays a role in sexual maturation and reproduction. It regulates gonadal function and the estrus cycle in animals by interacting with estrogen receptors.

Supplementation with melatonin has become popular for managing insomnia, jet lag, and sleep issues related to shift work. However, the effects of excess melatonin from supplements on reproductive health are not well studied. Appropriate melatonin dosing is important.


Melatonin use in cats

Melatonin is sometimes given to cats to help manage anxiety, stress, inflammation and sleep disorders. Some common reasons melatonin may be given to cats include:

  • Reducing anxiety such as during thunderstorms, fireworks, travel or vet visits
  • Helping with sleep issues such as insomnia or disrupted sleep cycles
  • Calming cats in heat or with other behavioral issues
  • Supporting healthy sleep patterns in senior cats
  • Decreasing inflammation from conditions like arthritis

The typical melatonin dosage range for cats is 0.5 mg to 1.5 mg per day. According to, a general guideline is to start with 0.75 mg for an average-sized adult cat, which can be repeated up to 3 times per day. The dosage may be adjusted up or down within the typical range based on the individual cat’s weight and response. It’s best to consult with a vet on the appropriate melatonin dosage for a specific cat.

The feline estrous cycle

The feline estrous cycle is the sequence of hormonal and physiological changes that occur as cats reach sexual maturity and become receptive to mating and breeding. Female cats typically experience their first heat cycle between 6 to 10 months of age.

The feline heat cycle consists of 4 stages that repeat every 2-3 weeks on average:

  • Proestrus – This initial stage lasts 1-2 days. The cat’s ovaries start maturing follicles and estrogen levels rise, leading to behavioral changes.
  • Estrus – Also known as being “in heat”, this stage lasts 4-10 days. Estrogen peaks and the cat exhibits mating behaviors – rubbing, rolling, vocalizing, and raising hindquarters.
  • Interestrus – Lasting 7-10 days, estrogen levels drop and the cat is no longer receptive to mating.
  • Anestrus – A period of sexual inactivity lasting 1-2 weeks until the next cycle.

During estrus, female cats become very affectionate, vocal, restless, decrease appetite, and have increased genital swelling and discharge. These signs alert male cats that the female is fertile and ready for mating.

If the cat does not become pregnant during estrus, the cycle will repeat every 2-3 weeks during breeding season, which is typically spring and summer.

Effects of melatonin on cats in heat

Research shows that melatonin may have beneficial effects for female cats in heat, primarily by reducing anxiety/restlessness and possibly suppressing estrogen levels.

Studies have found that melatonin implants and injections can reduce restless behaviors like excessive vocalization, attention-seeking, and motor activity that often accompany feline estrus. The calming effects of melatonin are believed to help decrease the stress hormones and anxiety associated with being in heat.

In addition, some research indicates melatonin may aid in suppressing the estrogen surge that triggers heat cycles in cats. One study found long-term melatonin treatment prolonged the resting phase between heats by about 1 week on average, suggesting possible suppression of estrogen production (Faya 2011). However, more research is still needed to fully understand melatonin’s effects on feline reproductive hormones.

Overall, melatonin shows promise for alleviating some of the behavioral and physiological effects of estrus in cats. However, owners should consult their veterinarian to determine if melatonin is appropriate for their cat’s specific situation.

Potential risks and side effects

While research has shown melatonin to be generally safe for short-term use in cats, there is a lack of extensive studies on the long-term effects of melatonin supplementation in felines. Since melatonin is a hormone that regulates sleep cycles, there is concern that prolonged use could disrupt a cat’s natural circadian rhythm and sleep patterns over time.

Some potential side effects that have been observed include drowsiness, lethargy, irritability, hair loss, and changes in reproductive cycles. However, these side effects seem to be uncommon when melatonin is used short-term and in appropriate doses.

It’s important to consult with a veterinarian about the proper dosage for your cat based on factors like weight, age, and health conditions. An excessive dose can increase the risk of side effects. Most experts recommend starting with a low dose around 1-3 mg for the average-sized cat, and monitoring for any adverse reactions.

Until more robust research on long-term safety is available, it is advisable to use the lowest effective dose of melatonin in cats and limit supplementation to short durations as needed. Continuous monitoring by a veterinarian is recommended. If any worrisome side effects develop, discontinue use.

Alternatives for calming cats in heat

There are several alternatives to using melatonin for calming cats in heat that can provide relief without medication:

Environmental changes like keeping the cat confined to one room with her bed, toys, litter box, and food can help minimize stimuli that get her worked up. Making sure she has vertical spaces to climb and places to hide can also help her feel more relaxed. Using synthetic feline pheromone diffusers and sprays in the home can have a calming effect as well (

The most effective long-term solution for feline behavior issues related to being in heat is spaying. Spaying cats eliminates the estrous cycle and prevents the hormonal fluctuations that lead to the restless, vocalizing behavior. It also eliminates the urge to escape and seek out mates. Spaying provides major health benefits as well, like preventing certain cancers and infections.

When to Give Melatonin to Cats in Heat

Before giving melatonin to cats in heat, it’s important to first consult your veterinarian. They can help determine if melatonin is appropriate for your cat’s specific situation.

Melatonin should only be used for short-term management of feline estrus cycles. It is not meant for long-term suppression. Melatonin can help temporarily reduce the intensity and frequency of heat signs in female cats.

Some key times when melatonin may be useful include:

  • Prior to a planned breeding – Melatonin can allow the owner to better control when a cat comes into heat.
  • For young or elderly cats not ready for breeding – Melatonin can temporarily suppress heat cycles until the cat is ready.
  • To provide a respite for chronic back-to-back estrus cycles.
  • To reduce stress and restlessness during travel or shows.
  • For household management when heat cycles are problematic.

Again, consult your veterinarian first before giving melatonin. Use it only as a short-term solution for feline heat management. Improper or long-term use of melatonin can disrupt normal hormonal function.

Correct dosage of melatonin

The correct dosage of melatonin for cats depends on the individual cat’s weight and needs. Veterinarians typically recommend starting with a low dose and monitoring the effects before increasing if needed. According to Basepaws, the general guideline is:

  • Cats under 10 lbs: Start with 0.5 – 1 mg
  • Cats 10-15 lbs: Start with 1 – 1.5 mg
  • Cats over 15 lbs: Start with 1.5 – 3 mg

The dose can be given once or twice daily. It’s best to start on the lower end of the dosage range recommended for the cat’s weight and only increase by 0.5-1 mg increments if the lower dose is not providing the desired calming effects. The maximum recommended dosage per day is around 6 mg.

Since melatonin takes around 30-60 minutes to take effect, owners should monitor the cat’s behavior after giving a dose to see if it results in improvements in relaxation, less restlessness, and ability to sleep. If the desired effects are not seen, the dosage can be gradually increased at intervals of a few days. However, it’s important not to increase the dose too quickly or exceed the recommended maximum per day.

Monitoring the effects of melatonin

When giving your cat melatonin, it’s important to monitor them for any changes in behavior or health that could indicate side effects. Some things to look out for include:

  • Changes in appetite – Watch to see if your cat is eating more or less than usual after starting melatonin.
  • Lethargy – Melatonin may cause drowsiness in some cats.
  • Agitation or restlessness – Some cats may become more anxious or agitated when taking melatonin.
  • Vomiting or diarrhea – Melatonin can cause digestive upset in rare cases.

It’s also a good idea to have your veterinarian run occasional bloodwork to check your cat’s liver enzymes. Melatonin is metabolized by the liver, so liver problems could indicate a need to adjust the dosage (VCA Animal Hospitals).

Make note of any concerning side effects and contact your vet if they persist or worsen. With proper monitoring, melatonin is generally safe for short-term use in cats when given at appropriate doses under veterinary guidance.


After reviewing the effects of melatonin on cats in heat, it’s clear that more research is needed to determine if it can reliably help calm cats during their estrous cycle. While some anecdotal reports indicate melatonin may reduce restlessness and vocalizing in cats in heat, there is no definitive scientific evidence yet. Before giving your cat any new supplement, it’s essential to consult your veterinarian first.

There are some potential alternatives to consider before trying melatonin for a cat in heat. Providing more playtime and mental stimulation can help redirect some of that restless energy. Pheromone sprays or collars may also calm cats during heat cycles. Ultimately, the only sure way to eliminate heat cycles long-term is spaying. But in the meantime, focus on keeping your cat comfortable and discuss any potential supplements with your vet.

While more research is still needed, melatonin may offer some benefits for cats in heat. However, always consult your veterinarian before giving any new supplement. And be sure to consider safer alternatives like mental stimulation and pheromones first. With some extra care and patience, you can help your cat get through her heat cycles as comfortably as possible.

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