DR THOMAS STUTTAFORD

Underwater sex, although often used to jazz up a boring B movie, is usually too uncomfortable to be anything other than an occasional adventure that adds spice to life.

Typical of the real-life experiences is that of a patient of mine, a student in Canada. She had sex in a hot spring - something she found exciting - but she and her companion ended up with severely grazed skin and a mass of cuts from the surrounding rocks.

The discomfort of those injuries, however, was nothing compared with the irritation caused by insect bites. Clouds of hungry mosquitoes and midges couldn't believe their luck when they found so much pale, soft, smooth flesh from which to suck blood.

Sex in showers seems to be standard practice, but even love in the shower can be almost as cramped as in a rock pool. Modern baths are a better bet as they are often made to take two and have the taps in the middle, which otherwise can be as intrusive and uncomfortable, if less sharp, than Canadian rocks. If soap is used as lubrication, whether in a bath or in a shower, it will present the same problems as do the chemicals in a bubble bath.

In future, reserve your bath, without bubbles, for foreplay. Bubble bath, scented soaps, bath oils, deodorants and other chemicals may all cause irritation after sex, as can some soaps and detergents used to wash underclothes.

A woman all too easily develops inflammation and irritation of her vulva and vagina when they are exposed to chemicals; she can be in trouble even if the inflamed areas are not secondarily infected by thrush organisms. Bubble bath washes off the skin's natural oils and washes away the lubrication that her body produces so that sex is comfortable.

When you share a bath or shower, use simple or pure olive oil soap and plenty of lubrication - even without any added ingredient, water makes intimate contact more abrasive.

Once the soft tender mucus membranes of the genitalia become swollen and inflamed from irritation or abrasion, thrush, always present, multiplies and compounds the problem. If the genitalia are so swollen that urination is difficult, cystitis is apt to follow.

Some patients, who are using appropriate contraception, say that they like to have sex in the bathroom as it means that their bed is in better order afterwards - although a nasty attack of thrush seems a high price to pay for avoiding a change of sheets.

However, thrush is usually relatively easily treated; fungicidal creams such as Canesten are available over the counter at most chemists. If a man also treats himself before sex, he spreads the cream into all the female nooks and crannies where thrush spores may be lurking. If the cream doesn't work, Sporanox or Diflucan taken by mouth usually succeeds.

Men who are prone to inflammation and irritation after sex may have been affected by thrush. If the trouble starts almost immediately, it is likely that they have an allergy to their partner's thrush. But if the reaction takes a day or two to develop, they have probably developed an infection from it.

Either way, simultaneous treatment of both partners will sort it out.

Dr Thomas Stuttaford, The Times doctor, spent many years working in a genito-urinary clinic

SUZI GODSON

Sex in the bath is usually a rather gymnastic and uncomfortable exchange, and a strangely dry affair. Water washes away any natural lubrication, which increases the level of friction during penetration. This can irritate the delicate tissue in the vagina, making it more susceptible to thrush.

The secret to good underwater sex is lots and lots of lube. Water-based products, such as K-Y Jelly, are no good because they wash off. But silicone, a synthetic substance, which is not water soluble, retains its slippery properties making it ideal for extended intercourse and underwater sex. Silicone is not absorbed by the skin and rarely causes any kind of reaction; in fact, some brands, such as Sliquid Ride (£8.99, 125ml, www.lovehoney.co.uk ) advertise themselves as being 100 per cent vegan-friendly, non-toxic, free of hypoallergenics, glycerin and parabens.

Your wife could also try Yes Oil (£23, 125ml, www.yesyesyes.org ), a lubricant containing two rich organic butters, cocoa and shea, which impart smoothness and body; two emollient oils, organic sweet almond and sunflower, which confer a silky texture while also moisturising the skin; and, lastly, a little white organic bees' wax and some vitamin E which, as well as benefiting the skin, acts as a preservative.

Thrush affects three out of every four women at some point in their lives. The chances are that your wife went straight to the pharmacy where she forked out £12 for a Canestan or Diflucan pill or pessary. The UK's thrush treatment market is worth about £18million a year. However, much of that is misspent because the symptoms of thrush are the same as the symptoms of a host of other skin conditions, such as eczema or lichen sclerosis, which need to be treated with topical steroids rather than anti-fungals.

If your wife gets repeated bouts of thrush, she should make an appointment with her GP so that she gets an accurate diagnosis. If it does turn out to be thrush, you also must get checked out because men get it too and you could be reinfecting each other.

Standard advice to women who want to avoid thrush is to wear cotton underwear and avoid tight trousers, antibiotics, vaginal deodorants, penetrative sex, perfumed bubble baths, pentrative sex in perfumed bubble baths, etc, etc. More recently, doctors in the know have begun to advise women to try using all-cotton tampons too. Though brands such as Natracare are more expensive than other tampons, it stands to reason that the polypropylene, perfume and bleach in normal rayon, viscose and plastic sanitary products will irritate the delicate membranes in the vulva more than a natural fibre.

Similarly, think twice about what you put in your bath. The detergents involved in making scented bubbles have caused so many adverse reactions that children's bubble baths in the US must carry a warning advising that prolonged use can cause skin irritation and urinary tract infections.

We all love bubble baths, but when you and your wife next think of getting it on in the tub, add a few drops of ylang-ylang to an almond oil base instead.

Suzi Godson is author of The Sex Book (Cassell, £16.99) and The Body Bible (Penguin, £16.99)

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