Melatonin is becoming increasingly popular, whether as a natural sleep aid for insomnia, to overcome jet lag, or as a supposed "booster" for a healthy lifestyle. The hormone, which is produced by the body but also available synthetically as a dietary supplement, is said to do one thing above all: improve sleep. But is melatonin really safe? More and more health-conscious adults are wondering what side effects can occur and for whom taking it is truly sensible and safe. In this article, you'll learn everything about the effects, risks, and side effects of melatonin – scientifically sound, understandable, and suitable for everyday use.
What is melatonin and how does it work?
Melatonin is a hormone produced naturally in the pineal gland (epiphysis) in the brain. It plays a key role in regulating our sleep-wake cycle, our internal clock. Melatonin levels rise in the dark, making us feel tired. With the onset of daylight, production decreases.
Melatonin supplements are available commercially as tablets, capsules, drops, and sprays, either over-the-counter or prescription-only, depending on the dosage and intended use. They are primarily used to treat problems such as difficulty falling asleep, jet lag, or shift work.
Why do people take melatonin?
Especially in recent years, melatonin has become a popular solution for problems falling asleep and staying asleep. Many people buy the hormone because they:
- Difficulty falling asleep (e.g. due to stress or jet lag)
- Do shift work and therefore have to shift their natural rhythm
- Want to improve your sleep quality (e.g. in older people, as the body's own production decreases with age)
- Have hope for more energy and concentration during the day
But what many underestimate:
Although melatonin is a natural hormone, it is not a harmless "miracle cure." Like any substance that interferes with hormone balance, melatonin can have side effects, especially if used improperly.
How safe is melatonin? What are the typical side effects?
Numerous studies demonstrate that, with the correct dosage and short-term use, melatonin is well tolerated by most healthy adults. However, side effects can occur, particularly in cases of overdose or long-term use, and these should not be underestimated .
The most common side effects of melatonin are:
- Daytime sleepiness and drowsiness: If you take melatonin too late in the evening or in too high a dose, you may feel tired, sleepy, or unfocused the next day.
- Headaches: Some users report mild to moderate headaches after taking it.
- Dizziness: Brief disorientation or mild dizziness may occur occasionally.
- Gastrointestinal problems: Nausea, abdominal pain or diarrhea are among the rare but documented side effects.
- Irritability and mood swings: Especially in sensitive people or when the dosage is too high.
- More vivid dreams or nightmares : Changes in dream intensity have been reported by some users, presumably because melatonin affects REM sleep .
- Changes in blood pressure: In a few people, melatonin may temporarily cause a decrease or, more rarely, an increase in blood pressure .
The side effects usually disappear quickly after discontinuation or correction of the dose.
Who needs to be particularly careful?
Although melatonin is considered safe for most adults, certain groups should only take it after consulting a doctor, or sometimes not at all, in order to avoid melatonin side effects as much as possible.
Attention should be paid in particular to:
- Pregnant and breastfeeding women : There are currently no conclusive long-term safety studies, therefore use during pregnancy and breastfeeding is not recommended.
- Children and adolescents: The long-term effects in young people have been poorly studied. Melatonin should only be prescribed to them on medical advice.
- People with epilepsy, autoimmune diseases or depression: Melatonin may affect the clinical picture and interact with other medications.
- People who take blood-thinning medication, sleeping pills or certain antidepressants: Here, too, consultation with the treating physician is mandatory.
What does science say about long-term use?
While short-term use of melatonin is generally considered safe, as shown by numerous clinical studies, its long-term safety remains a subject of ongoing research. Especially because melatonin is freely available as an over-the-counter dietary supplement in many countries, some people take it for months or even years, often without medical supervision.
Study situation in adults
Some controlled studies provide encouraging findings regarding the tolerability and side effects of melatonin during long-term use. For example, a systematic review by Ferracioli-Oda et al. (2013, published in the journal "PLoS ONE") found that melatonin is generally well tolerated in adults, even when taken daily for several months. The researchers evaluated a total of 19 studies with more than 1,600 participants and found no evidence of serious melatonin side effects or impaired endogenous melatonin production, at least at moderate doses (1-5 mg per day) and for periods of up to six months.
💡 Tip:
Cherry juice (especially sour cherry) can naturally support the body's melatonin production, making it ideal as a gentle alternative to direct ingestion.Limits and open questions
However, scientists also point out that many long-term studies are limited to averagely healthy adults and mostly only consider periods of a few weeks to a maximum of six months. To date, there have been hardly any independent, large-scale studies on long-term, high-dose use, especially in children and adolescents, pregnant women, or those with chronic illnesses. In particular, potential effects on hormone balance, metabolism, and fertility during very long-term use (over years) remain insufficiently researched .
Animal studies, for example, suggest that high melatonin intake can influence hormonal processes such as puberty, fertility, or the immune system. Whether and to what extent these effects are actually transferable to humans has not yet been conclusively proven .
Recommendations and caution
The practical recommendation of many researchers and physicians therefore remains cautious :
- Melatonin should be taken in the lowest possible dose and not on a long-term basis.
- Ideally, it is used for a limited period of time (e.g. in cases of jet lag, shift work or situation-related problems falling asleep).
- In case of chronic use or in case of uncertainty, it is always advisable to consult a doctor.
Source reference :
Ferracioli-Oda E, Qawasmi A, Bloch MH. Meta-Analysis: Melatonin for the Treatment of Primary Sleep Disorders. PLoS One, 2013 May 17;8(5):e63773. doi: 10.1371/journal.pone.0063773.
Are there any interactions with other medications?
Yes, melatonin can affect the effects of certain medications and vice versa. These include, in particular:
- Blood thinners (e.g. warfarin)
- Immunosuppressants
- Antidepressants and psychotropic drugs
- Antihypertensives
- Anticonvulsants (for epilepsy)
- Medications for diabetes
Anyone who regularly takes medication or has a chronic illness should only use melatonin after consulting a doctor.
Can you overdose on melatonin?
Although it is considered relatively safe, too high a dose of melatonin can increase side effects and even have a counterproductive effect:
Sleep problems, restlessness, and daytime fatigue increase rather than decrease. There is evidence that even small doses (0.5–1 mg) are sufficient to produce an effect, but many over-the-counter preparations contain significantly higher doses. Higher doses are rarely necessary.
Individual sensitivity and interactions
Older people, adolescents, and those with hormonal imbalances are often particularly sensitive. Melatonin can also intensify or alter unwanted effects when taken concurrently with medications such as blood pressure lowering drugs, antidepressants, or anticoagulants. In such cases, it is essential to consult a doctor before taking it.
In addition, alcohol, caffeine, and some medications can affect natural melatonin levels, distorting or weakening the effects of supplements. Therefore, those taking melatonin should maintain as uninterrupted sleep hygiene as possible, including avoiding screen light before bedtime.
How can the tolerability of melatonin be improved?
Anyone who wants to take melatonin should follow these basic rules to reduce the risk of side effects:
1. Start with the lowest effective dose possible.
2. Take melatonin 30–60 minutes before bedtime (not too late!).
3. Avoid combining it with alcohol or other sleeping pills.
4. Stop taking melatonin if side effects occur or your sleep problem does not improve.
5. Short periods of intake (a few days to two weeks) are usually sufficient.
6. If sleep problems persist, investigate the causes (e.g. stress, poor sleep hygiene) instead of relying on melatonin permanently.
Who benefits most from melatonin and when should it not be used?
Scientific recommendations currently focus on the following areas of application :
- For jet lag and shift work, to adjust the internal clock to new sleep times
- In age groups where there is proven reduced endogenous production and other methods do not help
- As short-term support for occasional sleep disturbances
Taking it "on suspicion" or without prior improvement of sleep hygiene is not advisable. In cases of severe sleep disorders, chronic illnesses, or accompanying psychological problems, medical supervision should always be sought .
Conclusion: Melatonin is not a harmless miracle cure!
Melatonin is a central regulator of our natural sleep-wake rhythm and has been proven in studies to be a generally safe and effective aid for short-term sleep problems, jet lag, and shift work disorders. Scientific studies indicate that, especially in healthy adults, melatonin is well tolerated in low doses when taken for short-term and even medium-term periods (over several weeks to several months) and generally does not cause serious side effects.
However, some questions remain, especially regarding long-term use over many months or years. Long-term human data, especially for sensitive groups such as children, adolescents, pregnant women, or people with chronic illnesses, are currently insufficient. The effects of overdoses and long-term high supplementation have not yet been fully clarified scientifically. Evidence from animal studies urge caution, as the hormone could potentially interact with other hormone systems, metabolism, or puberty .
Melatonin is not a cure-all, but when used correctly, it can be a supportive element on the path to better sleep and greater well-being. Long-term use requires genuine research into the causes and medical supervision, as good sleep is rarely a matter of a single preparation, but rather the result of conscious routines, lifestyle, and fine-tuning to individual needs .
FAQ: Frequently asked questions about melatonin side effects
1. Can melatonin be addictive?
No, according to current scientific knowledge, melatonin is not physically addictive. It is broken down in the body and does not affect the reward system like traditional sleep aids. However, psychological habituation ("I can't sleep without it") is possible.
2. What are the most common side effects of melatonin?
The most common side effects are morning fatigue, headache, dizziness, and occasionally nausea. These usually disappear after discontinuation or dose adjustment.
3. How long can I take melatonin at a time?
Most experts recommend short periods of use, ranging from a few days to a maximum of two weeks. Long-term use should always be under medical supervision.
4. Can I simply stop taking melatonin?
Yes. Healthy adults do not experience withdrawal symptoms after discontinuation. The body's own production returns to normal after a short time.
5. Is melatonin compatible with other sleep aids?
Melatonin should not be combined with other sleep aids, alcohol, or strong sedatives without caution. Interactions with various medications are possible, so always seek medical advice!
