Viagra's billion-dollar blind spot.

Viagra is widely regarded as one of the most spectacularly successful drug launches in pharmaceutical history. 

The first oral treatment for erectile dysfunction (ED), it was hailed as a 'marriage saver'. Within a year, it surpassed $1 billion USD in global sales.

Men were ecstatic. 

Women not so much. 

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But no one asked women what they thought about this 'miracle drug' – and this is why Viagra has broken as many marriages as it's helped. 

While pharmaceutical companies were busy coming up with a drug to help men regain the erections of their youth, absolutely no research was done on how to rejuvenate an ageing vagina. 

The result is men can now take a pill and – behold! – springing up in front of them is the penis of their youth! 

No such wonder drug for women. Our vaginal canal remains a certain age with drier, thinner and weaker walls that make intercourse uncomfortable or painful. HRT, topical oestrogen, vaginal moisturisers and lube help alleviate some symptoms but nowhere near to the degree that ED drugs help his erection. 

Put bluntly: his new rock-hard penis is no match for an ageing vagina. 

Viagra, Cialis and Levitra – collectively called PDE5 medications — help to dilate the arteries in the penis. This enables blood to pump into the chambers, making the penis hard and creating an erection.

Even better, this one can trump his 25-year-old version, because ED (erectile dysfunction) drugs tend to also have an excellent/awful (depending on your perspective) side effect of prolonging ejaculation.

It takes between two and seven minutes for a younger man to ejaculate during intercourse. An older man with a drug-induced erection can take up to 30 minutes.

This is great news if you've been a premature ejaculator all your life and are still sleeping with an enthusiastic 25-year-old who happens to love penetration. Not so good if the person you're having sex with is 55 with a vagina that can hardly stand two minutes of friction, let alone hard thrusting that never seems to end. 

Only 20 per cent of women orgasm through penetration only. The other 80 per cent climax through skilled, consistent clitoral stimulation.

That's not to say we don't enjoy intercourse – we do. But it's not how most women climax. Despite this, intercourse remains the main event when most couples have sex.

None of the pharmaceutical companies asked women what they wanted from their men. The truth is, most women over 45 don't want their partners to get rock-hard erections.

By the time most women are dealing with ED, plenty feel they've had enough of sex on his terms.

Things are improving, with younger men far more educated about female sexuality and open to feedback on what makes a woman orgasm. But older men, not so much.

A high majority of women over 45 have spent nearly all their sexual life tiptoeing around that 'fragile' male ego. Not complaining when sex results in one orgasm (his). Lots of older men get offended if they're 'told what to do', so women stay silent as he completely misses the spot when he does give oral sex.

Plenty of women spend their sexual lives satisfying themselves solo with a vibrator and basically putting out purely to keep their partner happy.

Her menopause and his erection difficulties can hail the end of decades of sex that's not satisfying or enjoyable for her. At last, a light at the end of the tunnel! Then along came the PDE5s and the prospect of never-ending sex based even more around intercourse. 

Is it any wonder plenty of women feel angry rather than pleased with the invention of ED medications?

"I've put up with having sex to please him for a long, long time. Not once has he asked if I'm satisfied," a 52-year-old woman told me.

"He does the same thing every time, uses the same ineffective techniques and has never once questioned whether I'm faking. I stopped faking years back and he hasn't even noticed I don't groan anymore. I did all that for him. What I'm not prepared to do is have sex purely for his pleasure when it hurts so badly, my vagina bleeds. I'm done."

Victoria Lehmann is a sex therapist who has decades of experience treating men with ED. She says she watches the expressions of the couple sitting in front of her as she explains how effectively the drug can work.

"His face lights up, hers often falls."

Who can blame us? Plummeting hormone levels reduce desire and make it harder for older women to get aroused and achieve orgasm.

Watching his erection get weaker is often a godsend, not a problem. If he can't have an erection, you'll either not have sex at all (which lots of women with low desire are very happy about) or focus on foreplay. For women, this inevitably results in better sex and more orgasms.

If you can get men past the 'sex equals putting my penis inside something', they enjoy it, too. But this is easier said than done.

ED medication makes sex even more focused on his pleasure, not hers – just at the point when it could have gone the other way.

"It takes an extraordinary amount of time to convince a man to have any form of sex – oral, hand-jobs, kisses, anything – if they aren't getting an erection," Victoria says.

"I wouldn't enjoy sex without an erection. Simple as that," says James, a 53-year-old man who started taking ED medications when his erections became less dependable. "But you don't need an erect penis to have a great time in bed," I counter, trotting out a line I estimate I've used about 5,000 times in my career.

"That's from the woman's perspective," he says.

"She doesn't need a man to be erect to get pleasure from oral sex, for instance. But a man needs an erection to be aroused while giving her oral sex. Even if you know sex isn't going to include penetration, an erection is necessary. It's not a macho thing, it's a physical thing. The blood must pump into the penis for men to feel any desire at all."

Most of the time, when I interview someone about sex, we have a laugh about something or another. But I learnt – fast – not to attempt any type of joke about a penis that refuses to obey its owner. 

I interviewed many men about sex and ageing for my latest book (Great Sex Starts at 50) and only a smattering had even remotely come to terms with having erections that weren't 'like they were'. All were equally resistant to the idea that sex could be good without an erection.

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Men get aroused by GETTING an erection. Yep, I've got that message loud and clear after writing about sex all my life. But while he's popping a pill and instantly in the mood for sex because one appears, what are women supposed to do? There is no pill to instantly arouse us.

It's important that men realise they are coming to the bedroom from the opposite end of the arousal scale, hot to trot, than their partner, who is usually coming in cold. 

A lot of people who know their stuff sexually believe the use of ED medications is reinforcing bad habits and encouraging bad sex. 

"The drug companies focus on men, they aren't asking the thirty million women who will be on the receiving end of those erections," sex therapist and author of 'She Comes First', Ian Kerner says.

He agrees we're working against nature using PDE5 medications. A softer erection is kinder to an older woman's vagina. The two work well together. A rock-hard, fist-sized erection? Not a match made in heaven.

Many women said ED drugs make their partner's erections too hard. He might be overjoyed to look down and see a raging hard-on. To his wife, it's about as sexy as knowing you're about to be penetrated by a red-hot poker.

Worse, lots of women feel they don't have the 'right' to refuse sex under these circumstances.

ED drugs aren't cheap. If he takes one 'as a surprise' (as one man told me, not realising his wife hid her dismay when she found out), women feel enormous pressure to have penetrative sex even when it hurts or they have no desire to have it. 

Marriages are being broken because of ED drugs. Some men are so determined to use their new youthful erections, if their wife refuses to play along, they go outside the relationship to test drive.

"When I found out he'd cheated, that was his excuse," a 48-year-old woman told me. "His defence was, 'What did you think would happen when you kept refusing me? I'm not letting this go to waste'."

Feeling pressured to have sex isn't the only consequence of ED drugs. Some men take them without suffering side effects, but most men get something. "A big red head," is how one man put it to me. (The one on his shoulders, just to be clear.)

I can spot a man who's taken ED medication: he looks flushed with fleshy, purply lips. His penis also takes on a purple tinge and hardens differently than it does naturally. Lots of men get headaches; some get tired, others find their tolerance to alcohol changes after they've taken a pill. 

"It's made sex even more of an effort," said one 59-year-old woman.

"Our entire day now gets planned around it. We can't go out for a boozy lunch, like we used to before sex, because ED medication doesn't work as well if he drinks too much. We can't enjoy a nice meal because it doesn't work on a full stomach. Afterwards, he feels tired and not up for doing anything and his face is bright red, so he feels embarrassed going out. All this just so he gets erect for about twenty minutes! I'd rather enjoy the day and have sex without an erection."

Obviously, not all women have bad experiences with ED medications. Some say it is the marriage/sex saver the pharmaceutical companies would have you believe. The plain cold reality is lots of men won't consider having sex without an erection and ED drugs help between 60 and 70 per cent of men achieve this.

"The minute he couldn't get an erection, his whole attitude to sex changed," said one woman. "It became 'What's the point?'. This lasted for two years. Then one day, out of the blue, he starts kissing me passionately and I could feel he had an erection. I asked him if it was from ED medication and he told me not to 'spoil it' by asking'. So, I don't. I'm just grateful it's brought him back to bed."

"It makes him relax." 

"It gives him confidence." 

"It makes him feel like him again. Like when he was young."

These are also comments women have made when I broach the topic of ED medications.

Victoria believes they are useful. "It can be easier to slip in a hard penis than stuff in a soft one," she says pragmatically. "But it has to be spoken about, you must use lube and test drive the vagina: massage inside first, to make sure she's ready." 

Other experts believe medication just makes it easier to get things going in an erotic direction.

Shame it seems to be travelling the wrong way.

Feature image: Getty.