The Arches in Glasgow said its over-18s policy would re-start on May 3.
The nightclub introduced the older age policy following the the death of Regane McColl in February.
The 17-year-old from Duntocher, West Dunbartonshire, died in hospital. Police linked her death to an ecstasy-like "Mortal Kombat" tablet.
Announcing the policy change, the venue said: "The Arches is reinstating its over-18s clubs policy from Saturday, May 3, 2014, with valid ID required for entry.
"We are working closely with Police Scotland in adopting many operational recommendations which we believe will provide a safer clubbing environment.
"The Arches operates a strict zero tolerance drugs policy and is committed to protecting the health and safety of its customers, whom we urge to act responsibly at all times."
The Arches announced it was introducing the over-21s policy after reviewing policies while working with Police Scotland's licensing division to "do even more to ensure a safer clubbing environment" within the venue.
It said all club events would be open to over 21s only and valid ID would be required for entry.
Those under 21 who purchased advance tickets for club events were advised to return them for a full refund.
Four other clubbers were taken to hospital after swallowing the same pills.
Regane had spent her final hours clubbing with a group that included her cousin and her 18-year-old friend.
The friends had gone to The Arches for the Colours 19th Birthday Party, which featured a range of dance DJs including Tall Paul, Ferry Corsten and Benny Benassi.
They said they were together for most of the night, with Regane watching the DJs near the stage.
But the schoolgirl was separated from the group late in the evening.
After the incident, police issued a warning about the dangers of the pills, which have a red dragon embossed on them.