Regane MacColl, 17, from Duntocher, West Dunbartonshire, died after a night out at The Arches in Glasgow city centre. It is believed she had taken a "Mortal Kombat" tablet.
She collapsed during the night out and died the next morning at Glasgow Royal Infirmary.
The new door policy was announced following discussions with police.
In a statement, The Arches said: "Since the tragic events of February 2, The Arches has been working closely with Police Scotland's licensing division to review our policies and do even more to ensure a safer clubbing environment within the venue.
"With immediate effect all club events will be open to over-21s only and valid ID will be required for entry.
"Anyone under the age of 21 who has purchased advance tickets for future club events at The Arches should return them to the point of purchase for a full refund."
The club stressed the venue had a zero tolerance approach to drugs and remained committed to adopting the best methods to protect the health and safety of its customers. However, it also urged them to act responsibly.
Almost 1000 friends and family attended the funeral last week of Ms MacColl, a sixth year pupil at St Peter The Apostle High, Clydebank. Her father Alastair paid an emotional tribute to his daughter. Mourners filled all 500 seats in St Mary's Church in Duntocher, while Father Joe Mills said a further 500 stood in the aisles and even outside the packed chapel.
Police in the west of Scotland have since made three ecstasy seizures and arrested seven people, but say they are not currently being linked to Ms MacColl's death. Inquiries into her death are continuing.
Last week, a man became ill in Kirkcaldy, Fife, after taking a blue pill outside a nightclub. Police said it was not being linked to the Glasgow case, but said the man might have died had he not received swift medical attention.