Continuing Scotland’s reputation for outspending public services in England (courtesy of funding arrangements which transfer resources from taxpayers south of the border) the Scottish Medicines Consortium today approved the prescription of Pre-Exposure Prophylaxis ( PrEP) – the drug claimed to prevent the spread of HIV from infected people to their non-infected partners. The drug is expected to be made available to 1,900 people, at a cost to NHS Scotland of £450 a month each.

PrEP would be an inappropriate use of taxpayers’ money at the best of times, but coming at a time when the NHS is desperately short of cash it is an outrage that the taxpayer is being called upon to subsidise people to take irresponsible risks: namely having unprotected sex with multiple partners. The PrEP lobby claims that it will save the NHS money by reducing the number of HIV infections and therefore the very high cost of treating them. This is highly questionable. While trials have shown that the drug is quite effective at cutting infection rates in a group of gay men who were already having unprotected sex, what they do not show – and cannot show -- is the effect of human behaviour of making the drug freely available. If, as is pretty inevitable, PrEP encourages people to have unprotected sex where previously they would have used a condom, the NHS could well find itself with increased infection rates.

The PrEP lobby maintains that the drug is necessary because not everyone can be trusted to use a condom every time they have sex. But if they can’t be trusted to do that then they can’t be trusted to take PrEP every day, either. It is not a once-off treatment: in order to be effective it must be taken every day. Moreover, PrEP only protects against HIV infection. It does absolutely nothing to reduce the risk of contracting other sexually-transmitted diseases.

When anyone makes these points to the PrEP lobby – as John Humphrys did in part on the Today programme this morning – its standard response is to try to liken PrEP to the contraceptive pill. If the latter can be made free on the NHS, they assert, it is discriminatory towards gay people to deny them PrEP. An equally valid comparison would be to ask: if the NHS is going to start providing free drugs to protect people against lifestyle-associated risks should it not also be handing out free cycle helmets or skiwear? Should it be handing out free low tar, filtered cigarettes on the grounds that smokers might otherwise take to more dangerous roll-ups? There will be no bottom to the NHS budget if its remit is extended to protecting people against risk.

But back to the pill. True, heterosexual couples can avoid pregnancy by also avoiding unprotective sex -- and in that sense the contraceptive pill is a luxury which need not be provided on the NHS. But there is a slight difference in cost between PrEP and the contraceptive pill: the former costs £400 a month to supply a single patient, the latter £10 a year. If you are liable to pay NHS prescription charges you are paying far more for the pill than it costs the NHS to supply it.

So if this is a question of discrimination there is a pretty simple answer: stop handing out the contraceptive pill for free and make couples pay that whopping £10 a year. Ultimately, the NHS is going to have to charge more for the routine stuff – just as it already does for dentistry – in order to have money to treat serious illness. Charging for the pill – and refusing to supply PrEP – would be good places to start.