Alyssa Wachtler needed an EpiPen, and soon. Her 6-year-old son, Hudson, is allergic to peanuts and tree nuts, and he heads back to school in early September.

Her local pharmacy was all out, and the pharmacist didn’t know when that might change. Many of the others she called only had the brand-name product, not the generic that her health insurance covers.

Only after calling between eight and 10 pharmacies in her New Jersey area was Wachtler able to find a two-pack of the generic EpiPen—and it was the pharmacy’s last box. The treatment will expire months before the end of the school year, though, so she will be on the hunt for an EpiPen again. And she worries that EpiPen supply issues will persist, putting her child’s health at risk.

“Will I be able to get it at the time I need it?” she said. “I just don’t have confidence in that now.”

Many parents are likely to face these challenges as back-to-school season hits.

Mylan’s MYL, +0.63% brand-name EpiPen and the authorized generic, two widely used allergic reaction treatments, as well as Amneal Pharmaceuticals’ AMRX, +2.22% generic auto-injector Adrenaclick were added to the Food and Drug Administration’s drug shortage list in May. Another manufacturer, privately held Kaleo Inc., has not reported supply interruptions.

All three companies have product available but “there may be occasional spot outages,” FDA spokesperson Jennifer Dooren said. The regulator has been working with manufacturers and monitoring supply as the school year begins, she said.

Read: There’s a shortage of U.S. EpiPens and other allergic reaction treatments

About one in 13 children has food allergies, according to the patient advocacy group Food Allergy Research and Education. Parents say there is typically a scramble in late August to buy products that contain epinephrine, which can reverse a life-threatening allergic reaction.

Kids with allergies often need to have these products in multiple places, such as school, any after-school activities and at home, compounding the problem.

“We are concerned that the shortage has not gone away,” said Jen Madsen, FARE’s chief of staff and senior director of federal advocacy. “We were certainly hoping it would be fixed by now, and it’s not, which is unfortunate.”

Why the EpiPen is in short supply

Mylan’s EpiPen, along with its authorized generic, which is effectively the same product at half the price, are the dominant epinephrine autoinjector products in the U.S.

They make up around 10% and more than 60% of the market respectively, according to an analysis from the drug price-comparison platform GoodRx.

But today, EpiPen supply is “inconsistent and inadequate in meeting global demand, including in the U.S.,” Mylan President Rajiv Malik said last week, and “supplies will continue to vary from pharmacy to pharmacy and may not always be available.”

The problems date to major manufacturing issues at a Missouri facility that is run by Meridian Medical Technologies Inc., a Pfizer Inc. PFE, +0.43% unit. All U.S. EpiPen products are manufactured at that factory, Pfizer confirmed.

Meridian Medical Technologies “failed to thoroughly investigate multiple serious component and product failures... including failures associated with patient deaths and severe illness,” according to a Food and Drug Administration warning letter that was sent to the company in September.

Read more: FDA warns of serious manufacturing violations in letter to EpiPen manufacturing facility

The warning letter itself didn’t affect supply, Pfizer spokesperson Steve Danehy told MarketWatch in an email, but “new processes” put into place to fix the problems noted in the warning letter have had “some impact on manufacturing capacity.”

Supply of third-party components has also played a role, Danehy said, and he described supply problems as temporary.

Supply problems for a rival product, Amneal’s generic Adrenaclick, were due to a shortage of supply coming out of a third-party manufacturer—also Pfizer, Amneal Chief Executive Robert Stewart said on a recent conference call, calling it an “unfortunate situation.” The product makes up about 30% of the U.S. autoinjector market, according to the GoodRx data.

The supply problems, which Amneal has said relate to compliance issues at Pfizer, Pfizer’s 2015 acquisition of injectable-drug maker Hospira and challenges at the Hospira manufacturing operation, continued through the second quarter and last month.

As for what is behind these manufacturing challenges, FARE’s Madsen said her organization’s understanding is that “putting [epinephrine] into an autoinjector that is reliable and will fire when you need it to is a little bit of a technically-challenging manufacturing detail.”

Both Pfizer and Mylan have said that they are exploring stabilization options, though they haven’t explained what those might be nor provided a specific timeline; Amneal says it has been working with Pfizer.

The FDA last week also approved Teva Pharmaceutical Industries Ltd.’s TEVA, +1.11% generic EpiPen, which is set to be the product’s first true generic rival. Teva has not yet said the product’s price or when it may become available. It may not come in time for back-to-school season, though, as newly-approved products typically take at least a few weeks to come to market.

Related: Teva’s generic EpiPen was just approved in the U.S.

The government has also said it might turn to importing these products, though probably not in time for September. In a Fox Business interview, Health and Human Services Secretary Alex Azar referenced the EpiPen when discussing a potential policy that would allow importation of drugs to alleviate shortages.

Notably, EpiPen shortages have also been reported in Canada and the United Kingdom.

Related: Southwest Airlines bans peanuts—see how other airlines handle allergies

Parental concerns persist

Even if competing options are already available, some parents say they prefer Mylan’s products, because each product injects the epinephrine medication differently and school staff tend to have more experience with the EpiPen.

Lianne Mandelbaum, a food allergy advocate and parent to a 13-year-old son with peanut and antibiotic allergies, usually sends the Mylan product to her son’s school. She buys the Auvi-Q for other situations, including to keep at home.

Mandelbaum recently bought a generic EpiPen two-pack for school on her first try, at her local pharmacy. But it was the last one, she said.

“I was coming out of there like it was a bar of gold—making sure it was in my purse, that it was still there,” she said. “Why is there such a dearth of product at a time like back-to-school, when the company should know to increase production?”

Others in the food allergy community have told her about driving more than 50 miles to find EpiPen products, Mandelbaum said, and some have even been sharing news of new shipments at a particular pharmacy on social media.

FARE’s Madsen acknowledged the concern about buying rival products, but said that there’s a lot of information available about how to use the various options, including from manufacturers and FARE. Kaleo’s Auvi-Q also speaks to users to walk them through the process, she noted.

Parents who are offered another alternative auto-injector shouldn’t decline it because they aren’t familiar with the product, Madsen said.

FARE recommends looking for the products at independent pharmacies and grocery store pharmacies, which may be more likely to have stock. Schools often won’t accept an expired EpiPen, parents note. Those who are having trouble can also contact Mylan’s customer relations line, per the FDA’s recommendation.