Free home test kits for chlamydia and gonorrhoea are being given out as part of a health board trial.
Hywel Dda health board patients can order one of the 1,000 kits online and return the swab through the post.
Launched after Public Health Wales' (PHW) sexual health review, it will be evaluated for rollout across Wales.
Maude Agombar, 20, who had chlamydia, said friends who did not like going to the doctor would be "a lot more in control of their own sexual health".
STI kits can already be bought privately, but PHW said they were "expensive and therefore inaccessible to many".
Cardiff University student Ms Agombar discovered she had chlamydia after going to a drop-in clinic, which was done on a first-come, first-served basis.
She said staff were "really pleasant" but securing an appointment was "kind of a nightmare".
Ms Agombar said people were still embarrassed about visiting the doctor, and sitting in an STI clinic "freaks a few people out".
She said she waited almost two hours for an appointment and saw four people she knew while she was there.
Helen Munro, a consultant in sexual and reproductive health at Hywel Dda, said attendances at sexual health clinics in Wales had "almost doubled" in the past five years.
"We can't see those people all the time, every day, so this is an opportunity by which patients can… take the test in the comfort of their own home," she added.
Dr Munro said there was still "an element of stigma" about attending sexual health clinics and the idea was the test would complement clinics rather than replacing them.
Grace Withers, 21, deputy editor at Cardiff University's Tab student website, said: "The timings of the clinics are not so compatible with the student lifestyle - a three-hour slot once a week on a certain day is really difficult because, if you've got a lecture, then you've got to make a decision."
People wanting the test can go to the scheme's website and answer a few basic questions to check it is right for them before making an order.
Once they receive the kit in a discreet envelope, they carry out the swab test and send it away for analysis. They are then contacted with the results, with options for treatment if necessary.
Zoe Couzens, of the PHW Trust, said it would be evaluated to see if it was "the right thing for Wales", with people being asked to complete an online survey.