(FORTUNE Magazine) – With armed guards and metal detectors in some schools, peanut butter might seem a low-level threat. But many school districts aren't treating the creamy lunchtime staple that way. An increasing number have banned peanut butter--and related products--to protect the estimated 2.5 million students who have food-related allergies.

The number of children with peanut allergies in particular is increasing as awareness of the condition grows, according to executives at the Food Allergy Network. The allergic reactions can be pretty serious: Some kids get rashes after being exposed, others have difficulty breathing, and a few kids have even died after eating undetected peanut derivatives at school. One child in Richmond is reportedly so allergic that he can become severely ill after merely touching the hand of a person who has eaten peanuts.

The bans have presented a conundrum for some parents whose kids don't have a taste for much else. "My son's favorite snacks aren't allowed, so it becomes a problem," says Gayle Erickson, parent of a kindergartner at the Stratfield School in Fairfield, Conn. In that school district, administrators banned all peanut products from the classroom of an allergic child. That's just the start: The school has a litany of rules. Quaker rice cakes are prohibited because there's a chance they were made on the same assembly line as Quaker's peanut butter crackers. The lunchroom has a peanut-free table, and at snack time children who mistakenly bring prohibited items are separated from the rest of the group. Don't try to sneak in contraband PB&Js: Teachers check each child's snack and lunch bag every day.

So far the bans are not affecting the sales of the three major peanut butter brands. According to Information Resources, peanut butter sales have increased 3% annually over the past five years, reaching about $850 million in 1999.

Jif (made by Procter & Gamble), Skippy (made by Best Foods), and Peter Pan (made by ConAgra) all say they are aware of the problem and have launched programs to inform school officials about allergies. (Sample tips teach nurses and principals how to give epinephrine shots to treat kids who have an allergic reaction.) But representatives at Jif, for example, say they are making no recommendations as to what children should eat in place of peanut butter. We have one: How about something a little less messy?