It has hired Profero to develop the digital strategy, building on the success of the TV campaign created by Mother, which broke last year.
The campaign will position Frank as a friendly, confidential and non-judgmental authority for drugs information.
Web users will be directed to www.talktofrank.com, which was created as part of the above-the-line campaign.
Frank, which is run as a partnership between the DoH and the Home Office, was created following COI's appointment of Mother in 2002. It targets parents, carers and drug users.
Profero's appointment followed a five-way competitive pitch handled by COI Communications. Online media planning and buying will be managed by roster online media agency i-level.
At the start of the year Profero developed a major online advertising campaign for the Home Office to raise awareness of child protection on the internet.