Side Effects of Melatonin 

Melatonin is a hormone that is naturally found in the body. It is produces in the pineal gland, which is located at the base of the brain. As a medication, melatonin is usually made synthetically. It is available in different forms, such as in pill form or in a form that can be placed either under the tongue or in the cheek for dissolution, which allows the medication to be absorbed into the body quicker.

Melatonin is used for people who have a need to adjust their body's internal clock, such as in cases of jet lag, those who have daily work schedule changes, also known as shift-work disorder, and for people who suffer from blindness to be able to establish a day/night schedule.

Another use for melatonin is to help people who suffer from insomnia, which can be due to several different factors. There are supplements readily available in most pharmacies that are recommended for short-term use, although side effects are needed to be taken into consideration. As with all other supplements, it is necessary to consult your primary physician before using melatonin.

Possible Melatonin Side Effects


One of the possible side effects of melatonin is drowsiness. Ingesting a lower dose of the supplement can, in some cases, counteract the drowsy effect. But when you know what the exact effects that the melatonin has on your body, it is vital that you do not drive or operate any heavy machinery.

Sleep-Related Symptoms

Some examples of these symptoms include vivid dreams, nightmares and sleepwalking. Incorrect use and overuse is fairly easy with these supplements. This can happen when you take melatonin supplements in the preparation for bedtime approaching and then your brain naturally releases melatonin chemicals into the bloodstream upon entering your darkened bedroom. In this case not only have you ingested the melatonin supplement, but you also have the added melatonin chemicals that are naturally released from your brain in response to the darkened environment. This can therefore cause a disruption in your sleep/wake cycle. It is important to note that sleep side effects from melatonin will disappear upon the discontinuation of supplement use.

Hormonal Changes

One of melatonin side effects is that it can affect you hormonally, as well. Hormone levels that are controlled by the pituitary gland, such as luteinizing hormones and progesterone levels, can be affected through the use of melatonin. Pregnant women must always consult their physician before taking any medications, even over the counter ones, as well as any supplements, vitamins etc. Melatonin in excess can be harmful to the fetus, as the child may run the risk of developmental disorders. Women and men who are trying to conceive should also be careful, as melatonin can affect their ability to conceive. In women it can interfere with ovulation, and in men there is a risk of a decrease in sperm count and mobility and increase in the size of their breasts. Melatonin has been linked to a decrease in the sex drive of both sexes.

Mood Changes

You may experience changes in your mood as a result of taking melatonin supplements. These mood-changing side effects are in most cases associated with an overuse of or overdose of melatonin supplements. Some examples of these possible side effects include giddiness, sadness and an acceleration of any depression, which may possibly already exist. Some less common mood changing side effects include delusions, paranoia and hallucinations. As with all other supplements and medications, your primary care physician should always be consulted prior to use, and this is especially true for persons who have any psychiatric history including, but not limited to psychotic disorders and depression.

Blood Pressure and Blood Sugar

While using melatonin supplements, there is a possibility of side effects to your blood pressure and blood sugar. You may experience an increase in your cholesterol level due to the use of these supplements as well as a decrease in your blood pressure. Regular use of melatonin has also been linked to arrhythmias in some people. Melatonin use, even in low doses, can result in a reduction of tolerance to insulin, so therefore type 1 diabetics need to be especially careful. Even with approval from a physician, blood sugar levels need to be closely monitored due to this risk.

Drug Interaction

In addition to melatonin side effects, you need to notice some drug interaction. When you are taking other medications, you should consult with their physician prior to taking melatonin supplements. Pay attention to these medications: blood pressure medications, blood thinning medications, anti-inflammatory medications, birth-control pills, steroidal medications, and antipsychotic and anti-depressant medications, as they are known to react in a negative way when melatonin supplements are taken in conjunction with them. Other commonly used substances that should not be taken with melatonin supplements include tobacco, coffee and alcohol, due to the possibility of negative side effects when using together.

Disorientation and Risk of Seizures

Other possible melatonin side effects are disorientation as well as the risk for seizures. These are not considered common side effects, but with improper use of this supplement, such as overdose, these side effects are possible. Careful attention to dosing instructions is pertinent. If you have a history of seizures or a known seizure disorder, you should avoid the use of this supplement, unless your physician allows you to take it.

Risk of Autoimmune Disorders

Melatonin has been linked with the risk of contracting autoimmune disorders including Chron's disease and autoimmune hepatitis. People have reported such side effects as nausea, vomiting and stomach cramps after using melatonin.

Pregnancy and Breast-feeding

Breast-feeding women should not take this supplement as it may be ingested into their breast milk and melatonin supplements are not safe for infants. In pregnancy this can also be quite dangerous because it can as be ingested with other foods and affect the growth of the fetus.

Considerations of Taking Melatonin Supplements

With knowing the possible melatonin side effects, you need to know some considerations of taking melatonin supplements. Melatonin use, as with many other supplements, can have negative side effects. If you have a medical condition it is always necessary to consult your physician before ingesting any supplements. There is a common misconception that if something can be purchased without a prescription it is safe, but this is not true.

Dosing for melatonin should be carefully abided by. If you feel that the dosage you are taking is not working well for you, consult a physician before increasing, decreasing or discontinuing taking it. It is also recommended that when choosing a melatonin supplement, stay away from those that are made from animal sources. As there is a possibility of contaminants being in them, and those that are produced in a lab are much safer.