Vyvanse is made of lisdexamfetamine dimesylate, a molecule that combines the amino acid L-lysine with dextroamphetamine (d-amphetamine) in a chemical bond. This bond is the defining feature of the drug: your body has to break it apart before the medication becomes active, which is why Vyvanse is classified as a “prodrug” rather than a direct stimulant.
The Active Ingredient
Lisdexamfetamine dimesylate has a molecular weight of 455.60 and the formula C₁₅H₂₅N₃O·(CH₄O₃S)₂. In practical terms, it’s an inactive compound made of two parts: L-lysine, a naturally occurring amino acid found in protein-rich foods, and dextroamphetamine, the stimulant that treats ADHD and binge eating disorder. These two components are chemically bonded together so that the drug does nothing until enzymes in your gut and liver cleave off the lysine portion, releasing dextroamphetamine into your bloodstream.
This conversion process is what gives Vyvanse its long, gradual effect. Because the body can only break the bond so fast, the release of active dextroamphetamine is spread over many hours rather than hitting all at once. Vyvanse typically takes 90 minutes to two hours to kick in and remains active for 10 to 14 hours, making it one of the longest-lasting stimulant medications available.
Why It’s Built This Way
The lysine-amphetamine bond wasn’t an accident of chemistry. It was engineered specifically to reduce the potential for misuse. With older stimulant formulations, the drug could be crushed and snorted or dissolved and injected for a rapid, intense effect. Because lisdexamfetamine requires enzymatic processing in the digestive system to become active, snorting or injecting the powder doesn’t produce that same rush. The molecule is essentially inert until your body’s own metabolism converts it, which only happens at a controlled pace through normal digestion.
Inactive Ingredients in the Capsule
Beyond the active ingredient, Vyvanse capsules contain a short list of inactive ingredients: microcrystalline cellulose (a plant-based filler), croscarmellose sodium (which helps the capsule contents dissolve), and magnesium stearate (a flow agent used in virtually all tablets and capsules).
The capsule shells themselves are made of gelatin and titanium dioxide (a white pigment). Different strengths use different coloring agents to make them easy to tell apart. Depending on the dose, the shell may contain FD&C Red #3, FD&C Yellow #6, FD&C Blue #1, Black Iron Oxide, or Yellow Iron Oxide. Capsules come in seven strengths from 10 mg to 70 mg, each with a distinct color combination. The 30 mg capsule, for instance, has a white body and orange cap, while the 50 mg has a white body and blue cap.
Inactive Ingredients in the Chewable Tablet
Vyvanse also comes as a chewable tablet, which has a different set of inactive ingredients to make it palatable and hold its shape. These include colloidal silicon dioxide, croscarmellose sodium, guar gum, magnesium stearate, mannitol (a sugar alcohol used as a sweetener), microcrystalline cellulose, sucralose (an artificial sweetener), and artificial strawberry flavor.
Chewable tablets are available in six strengths from 10 mg to 60 mg. Rather than using color to distinguish doses, each strength has a unique shape: the 10 mg is round, the 20 mg is hexagonal, the 30 mg is triangular, the 40 mg is capsule-shaped, the 50 mg is a rounded square, and the 60 mg is diamond-shaped. All are white to off-white.
Dyes and Allergen Considerations
If you’re sensitive to artificial dyes, the chewable tablets are the cleaner option since they contain no FD&C colorants. The capsules, on the other hand, use several synthetic dyes depending on the strength. If a specific dye is a concern, your pharmacist can confirm which colorants are in your prescribed dose.
The official labeling does not list gluten or lactose as ingredients in either formulation. The capsule shells do contain gelatin, which is animal-derived, so this is worth noting if you follow a vegetarian or vegan diet or have religious dietary restrictions. The chewable tablets do not contain gelatin.
How the Dose Translates to Active Drug
One detail that sometimes confuses people: the milligram strength on the label refers to lisdexamfetamine dimesylate, not to the amount of dextroamphetamine your body ultimately receives. Because the lysine portion and the salt form add molecular weight, the actual amount of active dextroamphetamine released is lower than the number on the capsule. A 30 mg Vyvanse capsule, for example, does not deliver 30 mg of dextroamphetamine. This is why Vyvanse doses aren’t directly comparable milligram-for-milligram to other amphetamine medications.