Chicago ? Worried parents have bombarded the maker of Similac with phone calls and peppered Facebook and Twitter pages over fears about insects in the top-selling baby formula after millions of cans were recalled.

But the company said Thursday it’s unlikely any of the formula already sold is tainted, and doctors offered more reassurance: Even if babies drink bug-tainted formula, the chance for serious harm is slim.

“There’s no reason for parents to panic,” said Dr. Joseph Gigante, an associate professor of pediatrics at Vanderbilt Children’s Hospital in Nashville, Tenn. Symptoms might include a mild upset stomach, but he says that should last only a few days.