If you are looking to fill your prescription for the weight-loss drug Zepbound, pack your patience. There is a dire shortage of certain doses of Zepbound due to a “demand increase,” according to the Food and Drug Administration (FDA). Patients looking for the 5 mg and 12.5 mg doses of the drug will have to wait says the New York Post, or discuss alternative strategies with their doctor.

Those dosages will be in limited supply at least through the end of April 2024, according to the FDA’s Drug Shortages tracker, says MPR. Other dosages, such as the 2.5 mg recommended initial dose, are still available in pre-filled single-dose pens.

A spokesperson for Eil Lilly that manufactures Zepbound said that the company plans to boost production to address supply concerns.

“While we anticipate intermittent availability in the near term due to unprecedented demand, we expect our investments in manufacturing and supply to progressively increase production of Mounjaro and Zepbound throughout the second half of 2024,” said the spokesperson.

Last November, the FDA approved Zepbound as a weight-loss management drug for people with obesity. It’s marketed as a diabetes drug under the name Mounjaro as both medications have the same active ingredient, tirzepatide. Mounjaro’s availability is also limited to the increase in demand, despite the hefty $1,100 price for a month’s supply.

All of the medications currently being used for weight loss that include not only Zepbound and Mounjaro which is often prescribed “off label” to help people with obesity, but also Wegovy and Ozempic, which are manufactured by Novo Nordisk work the same way. The drugs slow down the movement of food through the stomach and curb appetite, which can lead to weight loss, says ABC News. The popularity of weight-loss medications has grown over the past two years, leading to intermittent shortages as the manufacturers scramble to meet demand.

"It's only the beginning for Lilly as Zepbound is overtaking Wegovy in US new prescriptions for for obesity treatment, with 77,590 new scripts in the first week of March — so securing supply is essential," said Nicolas Schmitz, senior manager and strategic market analyst at KBI Biopharma, according to BioPharmaReporter.