Students are being warned that a so-called ‘smart drug’ could interfere with contraception and, as a result, lead to an unplanned pregnancy.
It comes amid suggestions that there have been some unplanned pregnancies among Leaving Cert and college students who are buying modafinil online.
The drug is a commonly-used one, similar to Ritalin and Adderall, which can make someone less drowsy or sleepy - helping them to study longer.
However, there are concerns some students are buying the usually prescription-only drug online.
Deirdre Lundy, Sexual and Reproductive Health Expert and advisor to the HSE, told Newstalk Breakfast increased alertness isn’t the only impact the drug has on the body.
She said: "On the face of it, it seems like a really good idea and a benign drug - but it isn't.
“Unfortunately, like a lot of other prescription medicines, it affects the way the liver processes other drugs.
“As a result, people who take modafinil will find that certain form of contraception - including the combined pill, the ring, the patch, the mini-pill - may not work.”
The impact of the drug can last for a month after the last modafinil tablet is taken.
Deirdre said unplanned pregnancies have always happened, but new approaches to data-gathering mean officials are “much more aware” of the factors involved in such pregnancies.
Addressing students who may be taking or considering taking the drug, Deirdre said: “You’re making an educated decision here, so you’d better educate yourself before you do it.
“Modafinil is a prescription-only drug for a reason - if you went to the pharmacy, the pharmacist wouldn’t give you the modafinil without letting you know it could interact with other medicines.
“Lots of things can interfere with contraception. But if you’re going to take another medicine, make darn sure you’re on some other form of contraception - the injection, one of the coils, certainly condoms. Otherwise, you’re putting yourself at risk.”