Vicodin contains two active ingredients: hydrocodone, an opioid painkiller, and acetaminophen, the same over-the-counter pain reliever found in Tylenol. These two drugs work through different pathways in the body, and combining them produces stronger pain relief than either one alone.
The Two Active Ingredients
Hydrocodone is the opioid component. It works by binding to specific receptors in the brain and spinal cord that normally respond to your body’s own natural painkillers. When hydrocodone attaches to these receptors, it blocks pain signals and can produce feelings of relaxation or euphoria. This is also the ingredient responsible for Vicodin’s potential for dependence and abuse.
Acetaminophen is the non-opioid component. It reduces pain by lowering the production of chemicals called prostaglandins, which your body releases in response to injury or inflammation. Acetaminophen also reduces fever, though that property isn’t the main reason it’s included in Vicodin. The two ingredients target pain through completely separate mechanisms, which is why combining them allows for a lower dose of each while still providing effective relief.
Available Strengths
Vicodin and its related brand names come in several fixed-ratio tablets. The first number refers to the amount of hydrocodone, and the second to the amount of acetaminophen, both in milligrams:
- 5/325: 5 mg hydrocodone, 325 mg acetaminophen
- 7.5/325: 7.5 mg hydrocodone, 325 mg acetaminophen
- 10/300: 10 mg hydrocodone, 300 mg acetaminophen
A liquid form is also available at 10 mg hydrocodone per 325 mg acetaminophen in each 15 mL dose. You cannot adjust the ratio yourself. If your pain requires more hydrocodone, the acetaminophen dose rises with it unless your doctor switches you to a different strength.
Why the Acetaminophen Amount Changed
Older versions of Vicodin contained up to 750 mg of acetaminophen per tablet. In 2011, the FDA mandated that all prescription combination products containing acetaminophen could include no more than 325 mg per dose, with full compliance required by March 2014. The reason: acetaminophen is processed by the liver, and too much of it causes serious liver damage. Because people sometimes take multiple doses a day and may also use other acetaminophen-containing products without realizing it, the lower cap significantly reduced the risk of accidental overdose.
This is worth paying attention to if you take Vicodin. Many cold medicines, sleep aids, and headache remedies also contain acetaminophen, and stacking them on top of a Vicodin prescription can push your total daily intake into dangerous territory.
Inactive Ingredients
Beyond the two active drugs, each Vicodin tablet contains several inactive ingredients that hold the pill together, help it dissolve, and keep it stable on the shelf. According to the FDA label, these include colloidal silicon dioxide, starch, croscarmellose sodium, dibasic calcium phosphate, magnesium stearate, microcrystalline cellulose, povidone, and stearic acid. None of these are pharmacologically active. They’re standard tablet-making materials found in most oral medications. If you have unusual allergies to pill fillers or binders, the full inactive ingredient list is printed on the manufacturer’s label or available from your pharmacist.
Why Vicodin Is Tightly Controlled
Vicodin is classified as a Schedule II controlled substance under federal law, the most restrictive category for drugs that still have accepted medical uses. This wasn’t always the case. Until 2014, hydrocodone combination products like Vicodin sat in Schedule III, which allowed easier prescribing, including phone-in refills. The DEA reclassified them after analysis showed these products carry a high potential for abuse and can lead to severe physical or psychological dependence.
Under Schedule II rules, you need a new written prescription for each fill. Your doctor cannot call it in or authorize automatic refills. These restrictions exist because hydrocodone is one of the most commonly misused prescription opioids in the United States, and the tighter controls are designed to limit how easily the drug circulates.