Hydrocortisone is made by combining plant-derived sterols with microbial fermentation and chemical processing. The manufacturing process starts with raw materials extracted from plants like soybeans and wild yams, then uses a mix of chemistry and biology to transform those simple plant compounds into the finished hormone. Your body also makes its own version, cortisol, through a multi-step process in the adrenal glands.
How Your Body Makes Cortisol Naturally
Hydrocortisone is the pharmaceutical name for cortisol, the stress hormone your adrenal glands produce every day. The body builds cortisol from cholesterol through a chain of enzymatic reactions, primarily in the outer layer of the adrenal glands that sit on top of your kidneys.
The process begins when cholesterol is converted into a compound called pregnenolone, which serves as the master precursor for nearly all steroid hormones. From there, enzymes modify pregnenolone step by step, adding and rearranging oxygen and hydrogen atoms at specific positions on the molecule. One key intermediate is 17-alpha-hydroxyprogesterone, which gets further modified with hydroxyl groups at two more positions before becoming cortisol. The entire pathway involves at least five distinct enzymatic steps, each performed by a specialized enzyme. Your body produces cortisol in a daily rhythm, peaking in the early morning and dropping at night, with total daily output roughly equivalent to 15 to 25 milligrams of hydrocortisone.
The Plant Starting Materials
Industrial hydrocortisone production begins not with cholesterol but with plant sterols, compounds that are structurally similar to cholesterol but cheaper and more abundant. The most common raw materials are stigmasterol and sitosterol, both found in high concentrations in soybean oil. Percy Julian first identified a usable mixture of these sterols precipitating in soybean oil tanks back in 1939, and soybeans remain a primary source today.
Another important starting material is diosgenin, a sterol extracted from wild yams (particularly Mexican species of the genus Dioscorea). Diosgenin has a chemical structure that’s especially convenient for conversion into steroid hormones because it already has much of the right molecular framework in place. Other plant sterols used in the industry include campesterol and brassicasterol, though stigmasterol and diosgenin dominate commercial production.
The Marker Degradation Process
The foundational chemistry for turning plant sterols into steroids was developed by Russell Marker in the 1940s, and the process still bears his name. Marker degradation is a series of chemical reactions that strips away the side chain of diosgenin, converting it into a simpler steroid intermediate called 16-dehydropregnenolone acetate (16-DPA). This intermediate serves as a crucial branching point: from 16-DPA, manufacturers can steer the chemistry toward hydrocortisone, progesterone, testosterone, or dozens of other steroid drugs.
From 16-DPA, additional chemical reactions build up the specific oxygen-containing groups that hydrocortisone needs. The molecule requires hydroxyl groups at three precise positions (carbons 11, 17, and 21) plus a specific ketone arrangement. Getting those groups into exactly the right spots on the molecule is the central challenge of the entire manufacturing process.
The Microbial Breakthrough
The hardest step in hydrocortisone synthesis has always been adding an oxygen atom at the 11-position of the steroid ring. Chemically, this requires harsh conditions and produces low yields. The breakthrough came from the Upjohn Company, which discovered that a common bread mold of the genus Rhizopus could perform this exact reaction in a single biological step.
The mold’s enzymes insert a hydroxyl group directly into progesterone at the 11-alpha position, replacing what had been a difficult, multi-step chemical process. This discovery was transformative for the entire steroid drug industry. Before microbial hydroxylation, cortisone (a close relative of hydrocortisone) cost hundreds of dollars per gram. After Upjohn’s process was commercialized, prices dropped dramatically, making steroid medications accessible for widespread medical use.
Modern Production Combines Chemistry and Biology
Today’s manufacturing process is a hybrid approach. The early steps typically use traditional organic chemistry to convert plant sterols into key intermediates. Then microbial fermentation handles the reactions that are difficult or inefficient to perform with chemistry alone, particularly the hydroxylation steps. Finally, additional chemical steps complete the molecule and purify it to pharmaceutical grade.
The microorganisms used vary by manufacturer. Some rely on molds and fungi similar to the original Upjohn process. Others use engineered bacteria. One research milestone came in 2003, when scientists engineered baker’s yeast (Saccharomyces cerevisiae) to produce hydrocortisone directly from ethanol. This was a remarkable feat: the yeast built a 27-carbon molecule from a 2-carbon starting material, performing the entire biosynthetic pathway that normally requires the human adrenal gland. While this yeast-based approach demonstrated the potential of fully biological production, most commercial manufacturing still uses the hybrid chemical-microbial method because it offers higher yields at industrial scale.
Steroid-based drugs as a category are produced in enormous quantities. Global annual production of all steroid pharmaceuticals exceeds one million tons, making them the second-highest manufactured drug category after antibiotics. Hydrocortisone represents a significant share of that total, given its use in everything from over-the-counter creams to injectable formulations for adrenal insufficiency.
From Raw Chemical to Finished Medicine
Once the hydrocortisone molecule itself is synthesized, it goes through extensive purification to meet pharmaceutical standards. The U.S. Pharmacopeia sets specifications that manufacturers must meet, including assay testing to confirm the drug’s identity and concentration, plus impurity testing to ensure byproducts and degradation products fall within safe limits. FDA laboratories conduct surveillance sampling and testing of finished hydrocortisone products to verify compliance.
The purified hydrocortisone, called the active pharmaceutical ingredient (API), is then formulated into its final dosage form. For topical creams and ointments, it’s blended into a base at concentrations typically ranging from 0.5% to 2.5%. For tablets used in hormone replacement, it’s combined with binders and fillers and pressed into precise doses. For injectable preparations, it’s often converted to a more soluble form, hydrocortisone sodium succinate, before being dissolved in sterile solution. Each formulation type has its own manufacturing requirements, but they all start with the same API produced through the plant-sterol-to-fermentation pipeline.
Why Plant Sterols Instead of Animal Sources
Early steroid production in the 1930s and 1940s did use animal sources, extracting hormones from cattle adrenal glands or bile acids. This was expensive and produced tiny quantities. A single ton of cattle adrenal glands might yield only small amounts of usable hormone. The shift to plant sterols solved this problem by providing cheap, abundant starting material that could be processed at industrial scale. Soybeans, in particular, offered a reliable year-round supply of stigmasterol and sitosterol at a fraction of the cost of animal extraction. This plant-based foundation remains the backbone of hydrocortisone manufacturing worldwide.