The stock plunged 10 per cent to Rs 3,049.75 on BSE.
On NSE, shares of the company tumbled 8.53 per cent to Rs 3,098.60.
The stock was the worst performer on both the Sensex and the Nifty.
The regulator said it had found several violations with regard to current good manufacturing practices (CGMP) at three of its plants.
"At Dr Reddy's Laboratories' facilities, we identified significant deviations from CGMP for manufacturing of active pharmaceutical ingredients (APIs)... We found significant violations of CGMP regulations for finished pharmaceuticals," US FDA noted.