Jet lag

Medical information

Written and reviewed by a team of doctors. Dr Fox is regulated by the CQC, GPhC, & MHRA.

About jet lag and Melatonin

Melatonin 3mg tablets are licensed in the UK to treat and prevent jet lag. Melatonin helps regulate the body's day night rhythm - the body clock. If jet lag symptoms are not improving after 5 days, medical advice should be sought. Drinking alcohol can make jet lag worse.

How many tablets do I need?

A pack of 30 Melatonin 3mg tablets is sufficient to treat between three and six episodes of jet lag, depending whether one or two tablets is taken each day. Maximum of 16 treatments per year.

How to take Melatonin for jet lag

Adults only. At destination take one or two 3mg tablets daily at your usual bed-time. Take two tablets if one does not work. Not to be taken before 8pm or after 4am. Best taken with liquid (not alcohol) preferably on an empty stomach (no food for 2 hours before and after). Forgotten tablets can be taken late, but not after 4am. Do not take double doses.

Taking more than the recommended dose (overdose) is likely to cause drowsiness, headache, dizziness, and nausea. Seek medical advice.

Can anyone take Melatonin?

For adults only (over 18s). Some people with pre-existing medical conditions or taking certain medications should not take melatonin. This includes people with epilepsy, autoimmune disease, diabetes and kidney and live impairment. A full list of interacting medicines can be found in the patient information leaflet supplied with the melatonin tablets - includes sedatives, sleeping tablets, and antidepressants amongst others.

Melatonin and pregnancy, breastfeeding, and fertility

The effects of Melatonin on unborn babies and breast-fed infants is unknown and therefore Melatonin should not be taken in pregnancy or when breastfeeding. Women who might otherwise become pregnant whilst taking Melatonin must use effective contraception.

Side effects of Melatonin and cautions

As with all medicines, some people experience side effects, although in most cases these are not serious.

Serious side effects: If serious side effects occur, seek urgent medical advice. These include chest pain (uncommon – affecting 1 in 100); reduced red blood cells (anaemia), reduced white blood cells (increased risk of infection), reduced platelets (increased bruising or bleeding), disorientation, fainting, visual symptoms, feeling your heart (palpitations, pounding heart and blood in the urine (rare – affecting 1 in 1,000). Allergic reactions with swelling of the mouth and tongue can occur (frequency unknown).

Non-serious side effects are listed below. A full and detailed list can be found at in the patient information leaflet supplied with the medicine pack.

Common side effects (may affect up to 1 in 10 people): headache, drowsiness.

Uncommon side effects (may affect up to 1 in 100 people): irritability, nervousness, restlessness, abnormal dreams, anxiety, dizziness, high blood pressure, abdominal pain, upper abdominal pain, indigestion, mouth ulceration, dry mouth, nausea, itching, rash, dry skin, excretion of glucose in the urine, excess protein in the urine, feeling unwell, weight increase.

Rare side effects (may affect up to 1 in 1000 people): high levels of certain fat molecules (triglycerides) in the blood, altered mood, aggression, increased sex drive, memory impairment, restless legs syndrome, 'pins and needles' sensation, watery eyes, hot flushes, vomiting, wind, excess saliva, bad breath, inflammation of the stomach lining, nail disorder, arthritis, muscle spasms, passing large volumes of urine, prolonged erection that might be painful, inflammation of the prostate gland, thirst, abnormal levels of electrolytes in the blood.

Frequency unknown: hypersensitivity reactions, high blood glucose level, flow of milk from the breasts (also in men).

Reporting of side effects: If you have any side effects, talk to your doctor or pharmacist, includes effects not listed above. You can also report side effects direct using the Yellow Card system - yellowcard.mhra.gov.uk.

Dr Fox pharmacy supplies Melatonin 3mg medication on prescription – you are required to answer a short medical questionnaire before your order can be completed.

Authored 14 February 2020 by Dr Tony Steele
Former hospital doctor, GP, and medical director of UNHCR refugee camp.

Reviewed by Dr B. Babor, Dr A. Wood, Dr P. Hunt
Last reviewed 17 February 2020
Last updated 3 March 2020

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