Swimmer's ear

What are the symptoms? An itchy discharge from your ear.

What causes it? This is an infection. It results from you marinading your ears in pool or sea water, then baking them in sunshine.

How can I treat it? Prevention is important because it tends to recur. Keep water out of your ears; use earplugs when you swim. And don't be tempted to ease the symptoms by prodding about with a cotton bud as it will only make matters worse. If it doesn't settle down, it'll need treatment with drops or a spray containing anti-inflammatories and antibiotics. See your GP.

Juvenile spring eruption

What are the symptoms?

This mainly affects young boys and causes sore swellings, blisters or crusts on the ears, usually a day or two after exposure to the sun. Typically, it appears in spring or early summer and may recur.

What causes it?

It's an unusual sensitivity to sunshine. Boys are more affected because their shorter hair does not shade their ears from the sun.

How can I treat it? Sunscreens and hats will shield the sensitive ear skin. So, too, will long hair - this may be a good excuse for your son to adopt that hairstyle he has always wanted. Any cooling cream will help the rash.

Prickly heat

What are the symptoms?

An intense prickly, itchy rash, which keeps you awake at night. It may recur in the heat, and so can ruin holidays.

What causes it?

Blocked sweat ducts force sweat into your skin, causing the rash. Any environment that makes you particularly sweaty may trigger an attack - hence the holiday misery.

How can I treat it?

With difficulty. Keep as cool as possible, seek the shade, wear loose-fitting “breathable” fabrics and shower regularly. Calamine cream may ease the itch. Antihistamines help only because they make you drowsy, which means that you are less aware of the irritation. Preventionis key.

Sunstroke/dehydration

What are the symptoms? Malaise, headache, cramps, thirst, dry skin and small volumes of dark urine. Babies and the elderly are most at risk of serious dehydration.

What causes it?

Fluid balance disturbance - you're not putting in as much as you're losing. Which is hardly surprising on summer holidays: you're sweating, and possibly doing more exercise than usual. Alcohol is not an ideal fluid replacement.

How can I treat it?

Take time to acclimatise yourself and go easy on the booze and exercise. Keep cool and drink plenty of non-alcoholic fluids. But if you're feeling really ill - with vomiting or drowsiness - seek medical help.

Athlete's foot

What are the symptoms? Itchy, cracked skin between your toes. This may spread to the soles and sides of your feet.

What causes it?

A fungal infection. A day lazing around the pool means hot, soggy feet, an ideal microclimate for fungi.

How can I treat it?

Dry your feet thoroughly after swimming or washing, and avoid shoes that make your feet sweat. Better still, leave your feet exposed as much as possible. Antifungal creams are available over the counter. Continue the treatment for a week after the rash seems to have disappeared, as there may still be fungi present.

Insect bites and stings

What are the symptoms? Bites produce itchy lumps, often in clusters, which may take up to a day to develop. Stings produce more immediate, intense pain and redness.

What causes them?

Many summer insects bite. Some people are allergic to the insect's saliva, and so develop a marked itchy reaction around the bite, with swelling or blistering. Allergies to wasp or bee stings can be serious.

How can I treat them?

Cold compresses and calamine lotion are usually adequate. Mild reactions improve with antihistamines. A severe reaction - when your lip or tongue swells, or you have difficulty breathing - requires immediate medical attention.

Food poisoning

What are the symptoms?

Bellyache and diarrhoea, often with vomiting and a temperature, too.

What causes it?

Germs in the food, which the gut tries to flush through and squeeze out, hence the symptoms. Summer barbecues are high risk; food is left out of the fridge, the work areas are dirty, the burgers aren't cooked properly and the chef's drunk.

How can I treat it?

Fluid replacement is the key, with frequent sips of water or rehydration fluids from the chemist. Antidiarrhoeals such as loperamide are useful if you're spending most of your time on the loo. Prevention is more important, so observe basic food hygiene rules.

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