The usual dose is one 3mg tablet of melatonin but your clinician may recommend 2 tablets (6mg) if needed. When you arrive at your destination, take melatonin at your normal bedtime (but not earlier than 8pm and not later than 4am).

Take 1 Circadin tablet after food, 1-2 hours before bedtime for 2 to 4 nights on arrival in the new time zone for a maximum of 13 weeks. Swallow the tablet whole – do not chew, crush or divide it as doing so will interfere with the prolonged-release properties.You can use melatonin for up to 5 nights in a row.

Circadin should not make you suddenly drowsy – you should feel natural sleepiness between 1-2 hours after taking it.

Melatonin is a naturally occurring hormone and is commonly used as a supplement to help regulate sleep. While generally considered safe for short-term use, it can have side effects. The severity and type of side effects can vary depending on the dose, duration of use, individual sensitivity, and overall health condition.

Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Just because a side effect is stated here, it does not mean that all people using this medicine will experience that or any side effect.

1. Daytime Drowsiness and Fatigue

One of the most common side effects of melatonin is daytime drowsiness or feeling unusually tired during the day. This can occur if the dose is too high or taken too late at night, disrupting the natural sleep-wake cycle and leading to grogginess the following day.

2. Dizziness

Some individuals may experience dizziness after taking melatonin. This can be particularly concerning when engaging in activities that require alertness, such as driving or operating machinery.

3. Headaches

Headaches are another frequently reported side effect. The exact cause is not well understood, but it may be related to changes in blood flow or neurotransmitter levels influenced by melatonin.

4. Nausea and Gastrointestinal Issues

Melatonin can sometimes cause gastrointestinal discomfort, including nausea, cramping, and stomach upset. These symptoms are usually mild and temporary but can be bothersome for some users.

5. Mood Changes

In some cases, melatonin can affect mood. It may cause feelings of depression or irritability, especially if taken in higher doses or over prolonged periods. Conversely, some users report mood improvements due to better sleep.

6. Hormonal Effects

Since melatonin is a hormone, it can influence other hormonal systems in the body. There is some evidence suggesting that melatonin might affect reproductive hormones, potentially impacting menstrual cycles in women or decreasing libido. However, these effects are generally mild and reversible upon discontinuation.

7. Vivid Dreams and Nightmares

Melatonin can increase dream intensity, leading to vivid dreams or nightmares. This effect is likely due to its influence on the rapid eye movement (REM) stage of sleep, which is associated with dreaming.

8. Blood Pressure Changes

There is evidence that melatonin may influence blood pressure. It can potentially lower blood pressure in some individuals, which might be beneficial for those with hypertension. However, this effect could pose risks for those with low blood pressure or those taking antihypertensive medications.

9. Impact on Circadian Rhythms

If melatonin is not timed correctly, it can disrupt rather than help align your sleep-wake cycle. For example, taking melatonin too early in the evening can cause an early shift in sleep patterns, potentially leading to difficulties staying awake in the evening or waking up too early.

For full information on side effects and correct use, see the patient information leaflet. If any side effects concern you, or you are experiencing any of the side effects mentioned in the patient information leaflet whilst taking this medication, please contact our clinical team or speak to your GP.

Talk to our clinicians before taking Circadin:

• If you suffer from liver or kidney problems. Studies on the use of Circadin in people with liver or kidney diseases have not been performed. Speak to your doctor before taking Circadin.
• If you have an intolerance to some sugars.
• If you suffer from an autoimmune disease. No studies on the use of Circadin in people with auto-immune diseases have been performed; therefore, you should speak to your doctor before taking Circadin.
• Circadin can cause drowsiness and it may impair your ability to drive.
• Smoking may decrease Circadin’s effectiveness because the components of tobacco smoke can increase the liver’s breakdown of melatonin.

Do not take Circadin if you are pregnant, think you may be pregnant, trying to become pregnant or are breastfeeding. Talk to your doctor or pharmacist before taking this medication.

Get emergency medical help if you have signs of an allergic reaction to this medication. These include:

• Hives
• Dizziness
• Fast or pounding heartbeats
• Wheezing
• Difficult breathing
• Swelling of your face, lips, tongue, or throat.

It is important that you let us know which prescription, over-the-counter medicines and recreational drugs you are currently taking. You must also tell us about any other medical conditions that you currently have (or had in the past). This will help us ensure the prescribed medication is safe and appropriate for you to take.

For full information on warnings, medication interactions and contraindications, refer to the Patient Information Leaflet. Please read all packaging and the Patient Information Leaflet before taking any new medicine and inform our clinical team or your GP of medicines you are taking or intend to take.