Armfuls of confectionery are a delicious, sugary reward for dressing up as devils and witches to scare the wits out of the neighbours.
But trick-or-treating will become a "Halloween horror" for children unless parents take steps to protect their teeth, warn dentists.
The Royal College of Surgeons has issued tips to ensure rotten smiles are just for Halloween.
Prof Nigel Hunt said: "We don't want to spoil the fun."
But the dean of the faculty of dental surgery said the state of children's teeth was a "national scandal" and added: "We want to help parents make sensible decisions about letting their children eat sweets at Halloween and all year round."
His tips include:
- If children are given sweets on Halloween they shouldn't eat them straightaway, but save them to have with a meal at home to reduce the impact on their teeth.
- If trick-or-treaters visit you over Halloween, consider giving out alternative treats to sweets such as stickers or balloons.
- Limit the number of sweets you give out to each child - think about only giving one or two rather than a whole bag.
- If the child is thirsty, make sure they do not have sugary drinks, water is better.
- Even though they may be tired, make sure children brush their teeth with fluoride toothpaste before going to bed.
Prof Hunt said: "Celebrating Halloween by trick-or-treating has become very popular in the UK in recent years.
"As a parent myself, I know the delight children take in donning fancy dress and visiting the neighbours to collect as many sweet treats as they can carry.
"Unfortunately, those sweet treats can be a Halloween horror for kids' teeth, sugar is one of the biggest culprits for nasty tooth decay."
Children under the age of 10 have more than 179,000 teeth extracted each year and around a quarter of three-to-five year olds have tooth decay.
NHS Structures "Complex and Confused"
Mr Milburn said the current system was "confused and complex".
The review, for consultants PwC, called for a gradual evolution of the structures, saying those who worked in the health service supported reform.
But the Department of Health said its plan for the future would be "delivered within the NHS's existing structures".
The PwC report was critical of the changes introduced in 2012 by then Health Secretary Andrew Lansley, which have resulted in the creation of "myriad" national organisations, including:
- NHS England
- NHS Improvement
- Health Education England
- Public Health England
The consultancy said it meant hospitals and other services faced the "daunting challenge of managing competing requirements".
The review said many of the functions of these competing organisations could be gradually merged into one and in time regional bodies be created to take charge of budgets for the NHS and council-run care services.
It said this would aid integration between the two systems - seen as key to shifting care out of hospitals and coping with the ageing population.
The report acknowledged these changes would take up to a decade - but said the polling it had carried out with NHS staff suggested there was widespread support for reform.
Mr Milburn said: "Despite the best efforts of its leaders to make it work, the current national architecture is confused and complex.
"The artificial divide between health and social care makes as little sense as the division of labour between a myriad of national bodies.
"Organisational change is always a risk but without it, the move towards integrated systems will be undermined."
But the Department of Health said there was no need for more reform as there was "a plan for the future... that is being delivered within the NHS's existing structures".
It said this would be funded by the extra money being invested in the NHS during the Parliament.
Landmark Chronic Fatigue Trail Could Treat Two Thirds
A therapy that successfully treats two-thirds of children with chronic fatigue syndrome is being trialled for NHS use.
The disease affects one in 50 children, leading to mental health problems and missing school.
"If anyone has done a cross-country [run] or a marathon - that is how it feels all the time," said Jessica, 14.
The trial, on 734 children, will use intensive online therapy sessions to adjust sleeping habits and activity levels.
It also uses a form of behavioural therapy to help children with the disease adapt the way they live.
Studies suggest one in 100 children misses at least a day of class a week because of the disease.
When Jessica - not her real name - was 10, she missed the equivalent of a whole term in one school year.
She was diagnosed with chronic fatigue syndrome (CFS) - also known as myalgic encephalomyelitis (ME) - at the age of 11.
"I can't do the things my friends can do," she told the BBC News website.
"I've missed a lot of birthdays.
"When they have sleepovers, I have to sacrifice that.
"And I can only do mornings at school, so I miss a lot of lessons."
Prof Esther Crawley, a children's doctor and from the University of Bristol, said: "This illness is devastating. About 50% of teenagers are tired, but these children are different - they stop doing the stuff they want to do.
"The first thing they drop is socialising and fun things, then they drop school, so this is very different to teenagers just being tired."
Jessica's mother said: "It has been hell, it has been depressing.
"I have lost friends, she has lost friends.
"She loves Florence and the Machine and her best friends went [to watch the band play live], it is isolating because her friends were doing what her mind wants to do but her body cannot."
Prof Crawley is leading the FITNET-NHS trial, to see if online consultations work and are cost-effective for the health service.
It is being funded by the research wing of the NHS in England, but when the results are out all the devolved health services would then decide whether they wanted to introduce it.
Trials of the scheme in the Netherlands showed 63% of the patients given therapy had no symptoms after six months, whereas just 8% recovered without it.
The scheme offers behavioural therapy sessions to change the way children think of the disease and aims to reduce the time spent sleeping and sometimes cut activity levels.
The approach regularly receives criticism from some activists who argue it treats chronic fatigue syndrome as a disease of the mind.
Prof Crawley said: "A teenager might say, 'You are just trying to change my sleep', but do you know how much biology you actually change?
"Children who come to my clinic have low cortisol [stress hormone] levels in the morning, that is why they feel so terrible; by changing their sleep, we reverse that.
"The stuff we are doing is not a pill, but it might as well be."
Lizzie Horgan, 26, from Hertfordshire, is just getting back to work after being hit with chronic fatigue syndrome in 2015.
"One evening I came home feeling really unwell and passed out, I had no control over my body.
"I was initially really reluctant to take up the offer of cognitive behavioural therapy, as I assumed it was for something psychological, but actually it really helped me understand what was happening to my body.
"So I think the trial is really cool and really exciting."
The results of the study should be known in 2022.
Mary-Jane Willows, from the Association of Young People with ME, told the BBC: "It is a scandal, what other condition would you leave a child with - undiagnosed and untreated?
"And the trouble is the longer they are left, the more ill they become.
"This trial is hugely important, every day we are phoned by parents who are desperate to get treatment for their children."
Prof Stephen Holgate, from the Medical Research Council, said: "CFS/ME is an important disabling condition.
"It has been chronically underfunded for years; patients deserve high-quality research like this."