What Are the Side Effects to Melatonin?

Melatonin has become a go-to sleep aid for many people, but before incorporating it into your bedtime routine, learn about the side effects.

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Melatonin has become more popular in recent years among people who struggle for a good night’s sleep. Supplements are readily available over the counter, often packaged as candy-like gummies. But many people aren’t clear about what melatonin is or what it actually does. Moreover, most people don’t understand how it works or the potential hazards that can come with it. While it seems like a highly recommended over-the-counter supplement, is it safe? And what are the side effects of taking melatonin?

What is melatonin and how does it affect sleep?

Melatonin is a hormone created naturally by the body. Made by the pineal gland deep inside the brain, melatonin regulates sleep-wake cycles. Those are one of the cycles set by your body’s circadian rhythms, an internal clock that controls your body’s functions over a 24-hour period. Your body cycles through time awake and alert or tired and asleep due to hormone levels and biological functions, as well as external cues, known as zeitgebers.

Your entire body, all the way down to the cells, runs off these rhythms. After receiving light and dark signals from the eyes, the hypothalamus (which acts as your body’s control center) dictates rhythms. This is why it’s so important that you get outside in the mornings and reduce screentime at night, so as not to disrupt your rhythms.

As it gets dark, the brain then produces melatonin, telling the body that it should prepare for sleep. With consistency, the rhythms become set, so that the body cues tiredness and wakeups around the same time.

Is melatonin safe?

Melatonin is available in over-the-counter supplements to help overcome sleep difficulties. While the body’s natural melatonin is highest at night, some people add supplements as a sleep aid. The supplement is labeled as safe for short-term use and has a low risk of dependency like prescription sleep medications.

However, melatonin supplements are not regulated for consistency or approval. The FDA (Food and Drug Administration) regulates many over-the-counter and prescription medications. This ensures consistent, safe dosages regardless of brand, ingredients, or use. Many supplements, though, are not regulated. There may be inconsistent amounts of melatonin regardless of the labeling, as well as other ingredients present that are not listed on the label.

Despite this, the American Academy of Family Physicians (AAFP) still recommends melatonin as the first treatment choice for insomnia and sleep disturbances.

Can you overdose on melatonin?

The short answer is yes. Every form of medication has a lethal dose. Researchers haven’t been able to find this dose for melatonin yet, but this doesn’t mean it doesn’t exist. Too much melatonin can lead to side effects, but it’s very rare that an overdose of the supplement could kill you.

If you think you’ve taken too much melatonin, don’t panic. Melatonin moves relatively fast through your body. But if you begin to feel like your symptoms have gotten too strong, call your doctor, 911, or poison control. If your child has taken too much melatonin, call poison control right away.

What are the side effects of melatonin?

Melatonin is so widely used because it has a low risk of addiction or complications. But it does have side effects.

The most common side effects of melatonin include:

  • daytime drowsiness
  • headache
  • dizziness
  • “hangover” sensation
  • nausea

Less common side effects can include:

  • vivid dreams or nightmares
  • depression
  • mood swings
  • poor appetite
  • abdominal pain
  • diarrhea
  • constipation
  • irritability

What are the long-term effects of melatonin?

Though not a lot of information exists about long-term usage, current research suggests that adverse effects of long-term melatonin are typically mild (headaches, diarrhea, and lower and upper respiratory tract infections). Due to the lack of research into the sleep aid, there are still many unknown effects, including whether it’s safe long term or short term for those who are pregnant or chestfeeding, as well as children or people with dementia.

Drug interactions with melatonin

In some cases, melatonin can be helpful for remedying medication-related sleep issues, but in other cases, there can be contraindications when melatonin is combined with an existing medication. For all uses, it’s important to talk with your doctor before starting a supplement to make sure it won’t counteract with a prescription you’re currently taking. Here are a few prescriptions that could interact with melatonin:

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Antidepressant medications

Animal studies have shown that melatonin supplements reduced the antidepressant effects of certain antidepressant medicines (such as Prozac). More research is needed to know if the same thing would happen in people.

Blood pressure medications

Taking melatonin may reduce the effectiveness of blood pressure medicines like methoxamine and clonidine.

Blood-thinning medications (anticoagulants)

Melatonin may increase the risk of bleeding from anticoagulant medications.

Steroids and immunosuppressant medications

Melatonin may cause these medications to lose their effectiveness. While on any steroid or immunosuppressant, always consult your doctor before taking melatonin.

Birth control

Taking birth control may lead to an increase in the amount of melatonin your body makes. Therefore, taking additional melatonin could increase your levels of melatonin above the healthy range. Melatonin does not affect birth control efficiency however: There have been studies that suggest taking a 3 mg dose of melatonin may slightly boost your fertility.

Can you take melatonin while pregnant?

Melatonin is not recommended if you are pregnant, trying to become pregnant, or chestfeeding. Even though this is a naturally produced hormone, supplements can provide too much hormone. There is not currently enough reliable research to determine if even low doses are safe to take while pregnant or chestfeeding.

Dr. Shelby Harris, a licensed clinical psychologist certified in behavioral sleep medicine based in New York, reminds us that regardless of the reason for taking melatonin, “talk with your doctor before starting melatonin since it isn’t for everyone, and there can routinely be side effects.”

Melatonin for children

Do not give melatonin to children unless directed by their healthcare provider. While it can be helpful for some children, notably those with disrupted sleep or ADHD, it can be dangerous if not used properly. Appropriate dosing is necessary for short-term use and only low doses should be used if needed.

Melatonin and depression

The effect of melatonin on depression is still underresearched. However, the consensus is that melatonin does not cause long-term depression in those who have no history of depression. So far research does suggest that melatonin can sometimes worsen existing depression symptoms. Since melatonin brings energy levels down, it can contribute to feelings of depression.

Melatonin benefits

“Melatonin can help some people with insomnia, but it isn’t the cure-all most people think it is,” says Harris. “We also use it occasionally for shift work and jet lag, but the timing of it really is personalized as travel and work shifts can vary widely from person to person.” Harris notes that, for juveniles under the care of a medical professional, low doses of melatonin can be helpful. “Melatonin is also used with children who have disrupted sleep and autism or ADHD as there is a good deal of evidence showing that it can be beneficial.”

Melatonin is often taken for medication-induced sleep issues. Discuss this with your doctor to be sure melatonin won’t interact with the medications you take.

How much melatonin should I take?

Melatonin supplements are available in several doses ranging from 0.1 mg to 10 mg, though some research has found that dosing does not always match what is listed on the bottle. Work with your doctor or sleep professional to determine the dosing that is right for you, then plan to take it 30 to 90 minutes before your desired bedtime.

“In sleep medicine, we actually use very small doses of melatonin such as 0.5 to 1 mg, multiple hours before bed. This helps gradually shift the body’s clock for people with delayed sleep phase disorder. For example, when you sleep enough hours in a row at night, but it isn’t on the time clock that you’d like,” states Harris. “Anything more than 3 mg of melatonin is considered a hefty dose. If you need to keep taking more and more, it isn’t working.”

The amount needed can vary from person to person. However, high doses are not more effective. As Harris said, if you find you are taking increasing doses or seeking doses higher than what is recommended or available, the doses are not going to work. Continually increasing the dosage will not make it more useful.

Alternatives to melatonin supplements

Trista Best, registered dietician at Balance One Supplements, suggests looking at your overall health if you’re having sleep issues. Some sleep issues can improve by improving your wellness, including exercise, exposure to light, and, of course, your diet.

“Foods that prevent quality sleep are often rich in refined carbohydrates,” Best explains. “Simple carbs reduce serotonin in the brain, the chemical responsible for inducing sleep. These foods are typically processed convenience foods like pastries, crackers, chips, and pasta, and should be avoided close to bedtime.”

Foods can also promote sleep. Some foods like almonds, walnuts, and bananas, as well as tart cherries, contain natural melatonin. When eaten close to bedtime, these foods could help improve sleep.

Maintaining a healthy lifestyle through regular exercise and consistent routines can also help decrease sleep struggles.

What to know about melatonin

Melatonin is produced naturally by the body, but some people may lack the amount needed to get enough sleep. In these cases, melatonin can be supplemented to help improve sleep. If you are not getting sufficient sleep, talk with your doctor about whether melatonin is a good choice for you and will not negatively affect you in other ways, including with other medications you’re taking, as melatonin can have side effects and may not be suitable for everyone.