(CNN) Illinois Gov. JB Pritzker has signed a law that would require insurance companies to cover costs for kids needing EpiPen injections for cases of severe allergic reactions.

House Bill 3435 will take effect January 1, and would require companies offering health insurance policies in Illinois to pay for "medically necessary epinephrine injectors for persons 18 years of age or under."

In a tweet on Tuesday, Pritzker hailed the bill, saying, "This legislation takes a big step forward in protecting our children and families."

When administered during an anaphylactic attack, the pens deliver what can be a lifesaving dose of epinephrine, or adrenaline. The epinephrine helps open up the airways and reduce swelling.

In an email, Tonya Winders, who heads the Allergy and Asthma Network, confirmed to CNN that Illinois is the first state to mandate EpiPen insurance coverage.

Read More