Homesickness should not be an automatic experience for children staying in unfamiliar surroundings, say psychologists.
Many children are vulnerable to homesickness
In the journal Pediatrics they suggest simple steps, including the offer of counselling, could prevent it.
US surveys suggest 90% children staying at summer camps get homesick - 20% severely so.
Youth camps are not common in the UK, but experts say children staying long term in hospital could also benefit.
Dr Christopher Thurber, a staff psychologist at Phillips Exeter Academy, a boarding school in New Hampshire, said: "For over 100 years, camps and schools have patted homesick children on the back, tried to keep them busy and hoped it would go away.
"But research shows that it's healthier, and more effective, to think about prevention."
He, and Professor Edward Walton, an expert in paediatric medicine, have compiled a list of tips to parents and carers about preparing children for their stay away from home.
This includes telling children that homesickness is normal, encouraging them to write letters to home, arranging a practice time away from home and telling them to talk to staff if they feel homesick.
The advice also stresses the need to make sure that children take medicine for conditions such as attention deficit hyperactivity disorder or for behavioural problems on the trip.
Professor Walton said: "What parents say - and what paediatricians say - beforehand matters, and is very important for the intensity of homesickness."
Fun in hospital
In the UK, stays of even a few days in hospital can be a distressing time for children, and if homesickness takes hold, this can interfere with the success of treatment.
At Great Ormond Street Hospital for Sick Children in London, a strategy has been devised to make children feel as secure and comfortable as possible during their stay.
The hospital offers free overnight accommodation either in the same room as the child, or in the neighbouring newly-opened patient 'hotel'.
There is also a trained play specialist on every ward, whose job it is to created a relaxed environment for younger children.
A spokesman added: "Each ward has a social worker and psychologist assigned to it who are on hand to talk to children, and staff meet regularly to discuss individual cases."