The boys, all aged 16 or under and from the Hawick area, were taken to Borders General Hospital in Melrose from Tuesday onwards after suffering adverse effects from consuming the pills.
Police said they have all been treated and discharged from hospital.
A 19-year-old man from Hawick has been arrested in connection with the matter. He is expected to appear at Jedburgh Sheriff Court on Monday.
Police Scotland Inspector John Reid said: “Our enquiries into this serious incident are ongoing and we want the public to remain vigilant in case any of these tablets are still in circulation.
“Our message is clear that people should not take any medication of any sort that has not been specifically prescribed for them.
“Clearly, this pink tablet has had an effect on these young people to the extent that they have been hospitalised after taking ill.”