The maker of Botox said Wednesday it will pay $600 million to settle an investigation into its marketing of the drug for off-label uses, including for the treatment of cerebral palsy in kids.

The settlement brings to an end a Justice Department investigation into drug maker Allergan, Inc. for allegedly marketing Botox between 2000 and 2005 for uses outside of those it is approved for. Federal officials said Allergan paid kickbacks to doctors for recommending Botox for off-label uses, among other allegations.

While doctors can prescribe medications as they see fit, it is unlawful for a manufacturer to market drugs for uses other than those specifically approved by the Food and Drug Administration.

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In the settlement, Allergan will plead guilty to one misdemeanor charge of “misbranding,” the company said in a statement.

The use of Botox to treat spasticity and muscle tightness in children with cerebral palsy is controversial. Last year the FDA warned against the practice, citing reports of hospitalization and death in some children who were injected with the drug. But a pair of neurology groups said earlier this year that while there are risks, Botox can be an effective treatment.

Botox is typically used to remove wrinkles and is not approved by the FDA for the treatment of cerebral palsy.