Rubbing a gel into the nose may be a speedy way to boost men's libido and tackle impotence without causing their partners side-effects.
Researchers in Brazil are testing whether the gel, which contains testosterone, can treat men with a hormone deficiency. The theory is that this hormone given via the nose will be active in less than an hour.
Up to 12.8 per cent of middle-aged men in the UK and Europe have a testosterone deficiency, according to the European Association of Urology.
Levels of the hormone fall steadily in men at a rate of less than 2 per cent a year from the age of 30 to 40. This doesn't tend to cause problems early on, but a testosterone deficiency that develops later in life (late-onset hypogonadism) can sometimes lead to issues such as low libido, impotence, mood swings and irritability, loss of muscle mass and reduced ability to exercise, insomnia, weak bones and man boobs (gynaecomastia).
A recent study by the University of Edinburgh even suggested that having low levels of testosterone is a risk factor for diabetes regardless of weight as it changes the action of genes linked to insulin, a hormone that controls blood sugar levels.
Men with a testosterone deficiency, which can be diagnosed with a blood test, may be referred to an endocrinologist for testosterone replacement treatment.
This comes in the form of tablets, skin patches and creams. However, while these can be effective, they have downsides.
The new gel, called Nasotestt, is thought to be more convenient than current skin creams, which can transfer on to anything patients touch (including female partners, where it can lead to an increase in body hair and acne).
It may work faster, too, due to the dense blood supply in the nasal cavity. Researchers say this means lower doses of testosterone can be given, avoiding the side-effects associated with the tablet form, such as mood changes, oily skin and prostate problems.
Past research has shown delivery of testosterone via the nostrils can be effective and safe. A study at the University of Virginia, reported in the journal Andrology, revealed 90 per cent of patients treated with a gel had normal blood testosterone levels after daily use for varying lengths of time.
The study also found that the men's impotence lessened, their mood improved and the proportion of body-fat tissue dropped over one to three months.
In new research run by FBM Farma Industria Farmaceutica in Brazil, 228 men will be given the testosterone nasal gel or a placebo gel, or a testosterone cream or placebo cream to rub on their arms daily for two months.
Patients using Nasotestt will pump one dose into each nostril three times a day and massage the nostril to spread it so it can be absorbed into the bloodstream.
Commenting on the study, Professor Raj Persad, a consultant urologist with Bristol Urology Associates, says: Nasal absorption works well, and is less likely to contaminate partners.
Not only is it suitable for the ageing male with low levels of testosterone, but also for a large proportion of younger men who have had damage to the testes following cancer and chemotherapy.'
* MEANWHILE, shockwaves can effectively treat impotence, according to a report in the journal Urology.
Scientists at Beijing Jishuitan Hospital reviewed data from trials involving 637 men treated with low-intensity extracorporeal shockwave therapy for erectile dysfunction, and found it significantly improved performance scores. Improvements lasted for at least three months.
The technique involves a device that releases thousands of energy waves and is thought to help by increasing blood flow.