BERLIN (Bloomberg) - German drugs maker Merck KGaA is considering a sale of its allergy business as the German company seeks to reduce debt following the $17 billion takeover of Sigma-Aldrich Corp., according to people with knowledge of the matter.

The business, known as Allergopharma, may fetch about 600 million euros ($636 million) and could attract interest from drug companies and private-equity firms, the people said, asking not to be identified because the deliberations are private.

The process is at an early stage and Merck could still decide against a sale, the people said.

Sigma-Aldrich is the company's biggest deal to date and will let Merck reduce its dependence on drugs after more than a decade of failing to develop a new one.

The Allergopharma business focuses on diagnosing allergies and treating them by training patients' immune systems to be less reactive to substances such as mold and pollen.

A representative for Merck declined to comment.