Nytol vs Melatonin: Which Sleep Aid is Right in the UK?

Sleep disorders are on the rise across the UK, with millions struggling to fall or stay asleep. Among the most talked-about solutions are Nytol and melatonin. But which one is right for British sleepers?

This in-depth, neutral comparison covers how each works, their safety profiles, legal availability in the UK, and how they stack up in terms of effectiveness — with science-backed insights and NHS guidance throughout.

What is Nytol?

Nytol is a well-known over-the-counter sleep aid brand available in most UK pharmacies. It typically comes in two main formulations:

• Nytol Original: Contains diphenhydramine hydrochloride (an antihistamine with sedative effects)

• Nytol Herbal: A mix of valerian root, hops, and passionflower

Diphenhydramine, the active ingredient in Nytol Original, is also found in some allergy medications. It works by blocking histamine receptors in the brain, which in turn causes drowsiness. The herbal version aims to promote relaxation and sleep naturally.

What is Melatonin?

Melatonin is a hormone naturally produced by the pineal gland in the brain, primarily in response to darkness. It regulates the circadian rhythm — the body's internal clock that tells us when to sleep and wake.

Melatonin supplements aim to mimic this natural hormone, typically in tablet or spray form. Unlike Nytol, melatonin is not available over the counter in the UK. It is only available via prescription, usually for short-term treatment of jet lag or specific sleep disorders like delayed sleep phase disorder.

Key Differences Between Nytol and Melatonin

Feature	Nytol (Original)	Melatonin (Prescription UK)
Type	Antihistamine	Hormone replacement
Availability	Over-the-counter	Prescription only
Used For	General insomnia	Circadian rhythm disorders, jet lag
Onset of Action	20–30 minutes	30–60 minutes
Duration	4–6 hours	3–8 hours (depending on formulation)
Common Side Effects	Dry mouth, grogginess, dizziness	Vivid dreams, headache, hormonal effects

Effectiveness: What Does the Science Say?

Nytol (Diphenhydramine)

According to the NHS, diphenhydramine can be effective for short-term sleep problems. However, it may cause next-day drowsiness, and tolerance can develop quickly.

The American Geriatrics Society Beers Criteria® (2019 Update) advises against the use of first-generation antihistamines like diphenhydramine in older adults, due to their strong anticholinergic properties, which increase the risk of confusion, dry mouth, constipation, and falls.

Melatonin

Melatonin has more targeted effects on sleep timing and is often used when sleep cycles are disrupted, such as with jet lag, shift work, or delayed sleep phase disorder.

A 2013 meta-analysis in PLOS One found melatonin reduced sleep onset latency by about 7 minutes and increased total sleep time by about 8 minutes, on average. While modest, this effect can be clinically useful in specific populations.

NICE guidance recommends melatonin (Circadin) for short-term insomnia in people aged 55 and over, but notes limited evidence in younger adults.

Side Effects and Safety

Nytol Side Effects

• Can cause grogginess the next day

• Not recommended for long-term use

• May cause dry mouth, blurred vision, constipation, or urinary retention

• Not suitable for people with certain conditions (e.g., glaucoma, asthma)

  
  

Melatonin Side Effects

• Generally well-tolerated in low doses (0.5–2 mg is often sufficient)

• Can cause dizziness, headache, nausea, or vivid dreams

• Long-term safety is not fully established, though short-term use appears safe in most individuals

Melatonin should be avoided in those taking blood thinners, immunosuppressants, or hormone therapies without medical advice.

Legal Status in the UK

One of the biggest differences between Nytol and melatonin is how they're regulated:

• Nytol is classed as a general sales medicine (GSL) and can be bought without a prescription in the UK.

• Melatonin is a prescription-only medicine (POM) in the UK. The NHS prescribes it under certain conditions, but it is not sold legally over the counter.

This regulation contrasts with countries like the US, where melatonin is widely available as a dietary supplement.

When to Use Nytol

Nytol may be suitable if:

• Sleep troubles are occasional and short-term

• There is no underlying condition causing the sleep disruption

• The individual has no contraindications (e.g., certain medications, glaucoma, prostate issues)

It may help during times of stress or travel-related fatigue but should not be used long-term.

When to Use Melatonin

Melatonin is more appropriate if:

• A circadian rhythm disorder is suspected (e.g., delayed sleep phase)

• Jet lag is affecting sleep

• A healthcare provider has diagnosed insomnia related to timing issues

Because melatonin works on sleep timing rather than general sedation, it is not typically effective for stress-related insomnia or frequent night waking.

NHS Guidance

According to the NHS:

• Nytol and similar products can help in the short term but should not be used for more than a few days without consulting a GP.

• Melatonin is offered in specific cases and should be prescribed by a medical professional, especially in older adults.

Self-medicating with imported melatonin is discouraged due to inconsistent product quality and legal risks.

Alternatives to Nytol and Melatonin

Several alternatives are commonly used in the UK:

• Valerian Root: Herbal supplement with some sedative properties. Common in UK products like Kalms.

• Magnesium: Shown to aid sleep regulation, particularly in those with low magnesium levels.

• L-Theanine: An amino acid found in tea that promotes relaxation.

• Lifestyle Changes: CBT-I (Cognitive Behavioural Therapy for Insomnia), sleep hygiene routines, light therapy, and mindfulness all show high efficacy.

Final Verdict: Nytol vs Melatonin in the UK

Both Nytol and melatonin have roles to play in managing sleep issues, but they target different mechanisms and scenarios. Nytol provides general sedation for short-term insomnia, while melatonin helps reset the body clock for circadian-related disruptions.

Neither is a perfect solution, especially for chronic sleep problems. Consulting with a healthcare provider is always recommended before starting any sleep aid — especially if the issues persist for more than a few weeks.

For UK residents looking for safer, sustainable sleep solutions, it may be worth exploring non-pharmaceutical options, or reading up on natural alternatives like valerian or magnesium.