A gynecologist's guide to sex: Expert answers the 7 most common questions - from fighting infections to period sex to penis size

Dr Alyssa Dweck, author of The Complete A to Z for your V, said most of her patients are confused about how to avoid infections from sex
She said women ask her about UTIs, BV, dryness, and period sex
Many patients also ask whether a penis can be too big for their vagina
Here, she answers the 7 most common questions and how to deal with them

It may be a fountain of pleasure.

But for many women, sex can also come with painful and frustrating pitfalls.

The balance of vaginal bacteria is so delicate that, even if women do everything to stay clean and use protection, it can be difficult to avoid infections, dryness, or bad smells.

On the other hand, many women want to be spontaneous or adventurous - having sex in a pool, or having sex despite getting an unexpected period.

And some want to know: can a penis be too big?

According to leading gynecologist Dr Alyssa Dweck, author of The Complete A to Z for your V, these are some of the questions she fields every day from patients.

The vast majority of women who pass through her office in upstate New York ask her for advice on how to have an active sex life without the side effects, she says.

The questions concern all manner of scenarios, from day-to-day health to one-off situations.

Here, she outlines the most common issues, and what to do.

For many women, sex can come with painful pitfalls, and they don't know how to avoid them

1. HOW DO YOU AVOID A URINARY TRACT INFECTION?

'This is such a common question because it's very very common in women,' Dr Dweck explains.

Women have a more than 50 percent chance of suffering at least one urinary tract infection in their lifetime. Most women suffer multiple for years on end.

A UTI most commonly affects the urethra, though it can progress to affect the bladder (also known as cystitis) or kidneys (pyelonephritis).

It is caused by bacteria invading the urethra.

In some cases, it is a case of fecal bacteria moving from the anus to the vagina via underwear. In this case, bacteria from the large intestine, such as E.coli, leave the rectum and reaches the urethra.

However, it is highly common for women to get a UTI from sex, since bacteria from the penis can invade the urethra or the thrusting motion can push lingering fecal bacteria towards her urethra.

Symptoms are painful. They include:

Intense pain in the lower back
Intense pain in the vagina and pelvis
A constant urge to urinate, though not much urine comes out
Burning and painful feeling while urinating
Shaky, faint, tired
Dark, bloody or cloudy urine
Fever or chills

'The reason women are so prone to UTIs is because if you think about the anatomy, the vagina, rectum and urethra are all very close together,' Dr Dweck explains.

'Huge areas of bacteria colonize naturally and that's how the urethra can get infected.

'Guys, however, have really long urethras and it's not as close to the rectum.'

So how do you avoid one?

It is more common among women with multiple partners, rather than one partner.

But Dr Dweck insists that should not scare single women. There are some hacks to try:

PEE BEFORE AND AFTER SEX

'The myth really is true: urinate before and after sex. It's very, very helpful. Doing that naturally flushes the bacteria from the urethra,' she says.

'That way, when you're thrusting, there isn't bacteria to colonize in your urethra.'

TAKE CRANBERRY SUPPLEMENTS ALL THE TIME

'Women prone to UTIs should take cranberry supplements. Take one a day, every day.

'If you don't want to take supplements, drink cranberry juice or eat cranberry gummies.

'It makes the bladder more slippery to bacteria, especially E.coli.'

However, she warns, women should avoid any juices or gummies that are mostly sugar.

'Sugar in general can promote certain infections, you really want pure juice.'

2. WHY AM I SUDDENLY MORE DRY THAN BEFORE?

Vaginal dryness is particularly common when women hit menopause.

Reduced estrogen means that vaginal tissue can thin, weaken and shrink, which can make sex uncomfortable or even painful.

It can affect women of all ages, however.

The hormonal fluctuations during breastfeeding and pregnancy can trigger dryness.

Anxiety can also affect blood flow to the vagina, causing dryness.

And some women can suffer dips in their sex drive, causing dryness.

According to Dr Dweck, this is one of the most common problems patients need treating.

So how can you treat it?

VAGINAL CREAM

'Dryness can be very painful.

'Women may get tiny micro-abrasions near the urethra caused by dryness, and that can make them more prone to infection.

'In this case, I would recommend using a vaginal cream to treat the abrasions, and lower your risk of a UTI.'

LUBRICATE

'I know it sounds obvious but using a lubricant helps a lot,' she says.

'If you get the right one, a tiny bit goes a long way.'

Dr Dweck recommends using a silicone-based lubricant which contains vitamin E, to moisturize.

3. WHAT IS BACTERIAL VAGINOSIS AND CAN I TREAT IT?

Bacterial vaginosis (BV) is a disturbance of the natural balance of bacteria that live inside the vagina.

Sex with someone new, having multiple partners, and rinsing out the vagina with a bottle of liquid can all increase a woman's risk of getting BV.

Semen can also lower levels of protective bacteria, triggering BV.

However, it is not a sexually-transmitted disease or an infection like a UTI.

In fact, the reasons for a woman developing BV remains something of a mystery.

According to Dr Alyssa Dweck, the majority of women who pass through her office in New York ask her for advice on how to have an active sex life without the side effects

But the way it manifests itself is incredibly painful.

It causes an incredibly bad smell, discomfort, and pain.

But it also has a far more menacing side.

Women with BV have a higher risk of contracting STIs like gonorrhea, chlamydia, and HIV.

They also have a higher risk of pelvic inflammatory disease (which can lead to infertility) and other infections.

Pregnant women with BV or with a history of BV have a higher risk of delivered their baby prematurely or passing life-changing infections to her baby.

HOW TO AVOID IT:

STAY SAFE

'It's more common in women with multiple partners, and it can be prevented by using condoms,' Dr Dweck says.

CHANGE OUT OF WET CLOTHES

'Women who sit around in a wet bathing suit and workout clothes have a much higher risk.

'It is a very easy way for bacteria to build up and to affect the bacterial balance.'

HOW TO TREAT IT:

TAKE PROBIOTICS

The vagina is home to five different strains of bacteria.

Studies show that women with BV tend to have lower levels of a certain type of bacteria called Lactobacillus.

Women with BV should try to incorporate more probiotics into their diet, such as fermented foods or yogurts.

They should also steer clear of carbohydrates and sugar.

And they should seek a probiotic with a minimum of 10 million bacteria, ideally containing Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14.

4. CAN A PENIS BE TOO BIG?

'I love this question. Everyone asks it,' Dr Dweck laughs.

Despite all her patients' concerns, she insists there is nothing to be worried about.

'If you think about how accommodating the vagina is, considering we have babies, it would be highly unlikely that a penis can be too big for a vagina.

'During arousal, the vagina expands.'

Only if a woman is not fully aroused could there be issued with size and fit.

'Some women could be small and some men could be big. But not to the extent that there's an issue,' Dr Dweck says.

'Even though penises come in all sizes, most erect penises are about the same size.'

5. HOW DO YOU BEAT BAD SMELLS DOWN THERE?

Ultimately, Dr Dweck says, the myth is true: a vagina should be seen as a 'self-cleaning oven'.

'The vagina has stuff to keep it clean, naturally,' Dr Dweck explains.

'Our bodies work to keep the bacteria balanced.

'So, even if you are very concerned about smell, you have to remember that mild stuff goes a long way.'

She adds: 'There are some women who can literally use anything in their vaginal area and be fine.

'But for women who are sensitive, less is more.'

Instead of buying fragrant products and intensely scrubbing, Dr Dweck recommends:

Vitamin D supplements (studies show women lacking in vitamin D have higher risk of smelly vaginal odor)
Hydrate (fluids help dispel bad odor)
Boric acid suppositories (placed weekly to keep vaginal bacteria balance in check)
Probiotics (in your diet or supplements to keep vaginal bacteria balance in check)
Less fragrant products (to avoid irritants)
Less vigorous scrubbing (to avoid irritating the area)

She adds that you should make sure the area isn't smothered.

'The area should at least get some 'air-ation' if you will,' Dr Dweck says.

'You don't want to be wearing a tight pad or panty liners 24/7 365 days a year.'

6. CAN I HAVE POOL SEX WITHOUT GETTING AN INFECTION?

Dr Dweck said sex in different locations like the sea and swimming pools can be fun.

However, some types of chlorine can be an irritant, especially if it's caustic.

'In general, some women who have sex in very heavy chlorine pools do become quite irritated.

'The natural lubricant of the vagina may not be as high.

'So there is a very real risk of infection to watch out for.'

7. IS PERIOD SEX UNHYGIENIC?

'There's nothing wrong if you're comfortable with it. Some women just find it messy or gross,' Dr Dweck says.

'The infection risk would be if there's an inherent infection like HIV or hepatitis. If not, you're fine.'

In fact, Dr Dweck reveals, she thinks period sex can be great for women.

'The nice thing about period sex is that some women find that their libidos soar in that time. And orgasms may help with cramps.

'Women also feel very comfortable that - if their periods are regular - they can't get pregnant during their period, so that may make them more carefree, and help them feel aroused.

'It's really the mess factor which puts most women off.

'If that's the case, you can manipulate the lighting, or use a towel.

'Alternatively, this could be a perfect opportunity for shower sex.'