Botox treatment may also turn out to be a recipe for happiness.
As botulinum toxin A prevents people from frowning, it could indeed be actually makes them happier. It is thought that by preventing people from frowning, Botox injections also prevent the expression of negative emotions, resulting in a happier mood.
Experts at Cardiff University, who took part in the small-scale study, believe that the findings could lead the way to new treatments for depression.
Dr Michael Lewis, a senior lecturer at the university's school of psychology, said: "Botox works to make people beautiful by paralysing the frown muscles.
"We know from research in the past that if you make someone smile they feel happier.
"So, if you stop someone from frowning you would think that they are going to be less sad or unhappy."
Dr Lewis, who will present the research at the British Psychological Society's annual conference in Brighton, recruited 25 people to take part in the research, which was carried out with Court House Clinics, London.
Twelve received injections of botulinum toxin A to the forehead and the others had fillers, peals or other cosmetic treatments. All 25 participants completed a mood questionnaire at least two weeks later.
The research found that the patients who had received Botox treatment were significantly less depressed, anxious and irritable than the other group.
Dr Lewis said: "Both groups had had some form of cosmetic treatment, and there was no difference in how effective they thought their treatment had been, so this result is most likely due to the effects of Botox specifically."
Until now, Botox has been widely used because of its ability to smooth wrinkles.
Singer Bonnie Tyler is a fan of the procedure - she has previously said: "I've never kept the fact that I have Botox a secret - I've been having it for 11 years."
And model Linda Evangelista said in an interview with Vogue: "I'm pro-cosmetic procedure. I use Botox and I'm not afraid to say it, though I do like to keep some movement in my face.
"For me, it's just for enhancement, like hair colour or make-up or any other tricks you can do to make yourself feel better."
Dr Lewis added: "This research may help the development of a new treatment for depressive illnesses.
"Unlike other treatments for depression, which have significant negative side effects, the main side effect of a Botox-based treatment would be a younger-looking face.
"But as the cosmetic effect of Botox is temporary, so will be the emotional effect. As the effect of the Botox wears off, one's mood is likely to return to normal levels."
Professor Harryono Judodihardjo, medical director of the Cellite Clinic in Cardiff, told Western Mail: "We have always known that Botox is very effective because people keep coming back.
"This study suggests that there is probably more than it simply being effective and reasonably priced.
"This was a very small study and as such it is suggestive rather than conclusive, but it would appear to support other research into the use of Botox.
"We are in an economic depression but people are still coming - they are saying that they would rather cut back on shopping than stop having Botox."
Dr Alun Evans, a dermatologist at the Princess of Wales Hospital, Bridgend, added: "While the number of patients in this study was quite small, it shows an interesting and welcome side effect of Botox injections. Although we don't fully understand why patients feel happier after their treatment, it certainly fits in with what we see in the clinic."