Q. We've heard there is a tablet that prevents mountain sickness. Can children take it? We have always dreamed of going to the Himalayas or the Andes and now that our children are seven and four we were thinking about planning a trip.
Clare Morris, via e-mail

A. Any sane parent will be concerned about the risk of mountain sickness which, even in adults, is a very unpredictable foe. Yet the answer, unfortunately, isn't simply to pop some acetazolamide capsules, the medicine that can be taken to speed up acclimatisation. A lower-altitude trek would be a better idea, given that mountain sickness is rarely an issue below an altitude of 2,500m. At this kind of elevation mild breathlessness will be noticeable and everyone will feel less vigorous.

Going higher makes breathlessness and fatigue worse, so that by the time you have ascended to 3,000m everyone will be affected with some feeling particularly unwell. You are most likely to feel ill if you have ascended rapidly - for example by train, car or plane. Going higher still, brings on other symptoms of mountain sickness, including insomnia, and - more importantly - the risk of becoming seriously ill increases.

Indeed, a leader in the British Medical Journal written by paediatricians with extensive mountaineering experience suggested that small children should never be taken over 3,000m. The difficulty is not that children are more susceptible to mountain sickness, but that the first subtle symptoms are no different to crankiness as a result of boredom, hunger, fatigue or the cold. Children can deteriorate rapidly and become very ill so a middle-of-the-night evacuation to lower ground could be required to save a life. The risks are lessened by cautious planned ascents that mean spending several days climbing to 3,000m and then going up no more than 300m per day thereafter. I feel that until a child can explain why they are cranky, or where it hurts, any ascent higher than 3,500m is unwise.

With this in mind, Peru's Inca Trail - which takes hikers over 4,000m - wouldn't be a good trek with small children. There is probably more scope in the Himalayan region, where you can walk for a month without going much over 3,000m. It is not necessary to go as high as Everest base camp (at 5,340m), for example, to get a spectacular mountain experience. More varied and finer country is to be found towards Annapurna in Nepal. However, due to the ongoing political problems in Nepal, I'd advise you to refer to the Foreign & Commonwealth Office website (0845 850 2829; www.fco.gov.uk) for travel advice.

One Japanese father I know of took his one-year-old to the top of Island Peak close to Everest, which is over 6,189m. Fortunately the child survived, yet he risked not only mountain sickness but also hypothermia. There are child deaths in the Alps each year: the parent will be skiing or climbing while the child in the backpack freezes. So although children can take a drug to speed altitude acclimatisation, this is not the only issue. The sustained release capsules cannot be split but the tablets can. I've used this drug when trekking before having children but have never given it to my sons. We've always relied on slow ascents to keep safe and have found that Mars bars and Kit-kats are the best boosters for flagging children, as well as the very sweet Indian-made "Frooti" mango juice cartons.

On extended treks in Nepal, we have arranged child-porters, but even with this luxury, we were careful about the cold, and also sun protection. The advantage of a baby or toddler being carried is that she or he'll be out of the way of village guard dogs, which can be very vicious (and can be rabid), and they are less likely to fall off a cliff path, but even tucked up in a basket, a small child's temperature needs to be checked often.

We have taken our sons to modest altitudes on a dozen occasions but always on trips that allowed us to stop whenever the children wanted to. The main problem with going to high altitudes with children under the age of about 10, is that even if they are fit and enjoy walking and the outdoors, few are keen on getting to the summit. Most will want to play hide-and-seek, or climb rocks and trees or chase chickens or butterflies or frolic in streams.

Children who do not share their parents' goals get fed up. Despite the fact that we were experienced mountaineers before our family arrived and the fact that I have a lot of experience in paediatrics and child health, I found it astonishingly difficult to determine whether the children were experiencing significant problems or were just cheesed off.

Goal-driven holidays anywhere can leave children frustrated or bored and trekking with a group is probably the worst example of these: there will be times in the mountains when it is just not possible to stop because the children want to play or explore. The terrain will dictate where stops are possible and comfortable, and if there are time-constraints then there may be a drive to ascend too quickly to allow small bodies to acclimatise. Small children will enjoy a trek more at lower altitudes where there is village and bird-life to entertain, and the wind isn't so chilling, and in Nepal at least the views are still stunning.

Dr Jane Wilson-Howarth has worked in Nepal for six years. She has written 'Your Child Abroad' (Bradt 2005) and 'Bugs, Bites and Bowels' (Cadogan 2002)

Send your family travel queries to The Independent Parent, Travel Desk, The Independent, 191 Marsh Wall, London E14 9RS or e-mail crusoe@independent.co.uk

My Holiday In Grand Cayman

By Alexandra Nelson, Aged 9

We went to Pedro St James Castle. It is not a castle like in England, but is the oldest building on the island. It is the place where democracy was born in the Cayman Islands. I visited the Butterfly Farm and the Turtle Farm. I liked the Butterfly Farm because it was very colourful and you could walk around and watch the butterflies do their own thing. At the Turtle Farm, you could pick the turtles up out of their tank, but they splashed a lot!

I ate food from different countries around the world, including Italian, Cuban and Cayman-style food.

I liked it when we went to Queen Elizabeth II's Botanical Garden. There were unusual plants there, and they breed blue iguanas, because they're endangered.

My favourite place was the Stingray City sandbar. I swam in the sea with the stingrays and fed them squid. We went snorkelling and saw eels, parrotfish and angelfish.

It was mostly very sunny, but there was a hurricane that lasted for one day, before moving over to the US. The hurricane was called Hurricane Charlie.