Methadone’s active ingredient is methadone hydrochloride, a synthetic opioid. Beyond that single drug compound, the full list of ingredients varies widely depending on whether you’re looking at a tablet, a liquid concentrate, or an injectable solution. Each formulation contains different fillers, dyes, sweeteners, and preservatives.
The Active Ingredient
Methadone hydrochloride (molecular formula C21H28ClNO) is a fully synthetic opioid, meaning it’s manufactured in a lab rather than derived from the opium poppy. It works primarily by binding to the same receptors in the brain that other opioids target, relieving pain and preventing withdrawal symptoms. The drug actually exists as two mirror-image versions of the same molecule. One version is roughly 50 times more potent for pain relief than the other, but both versions share a second, less commonly discussed property: they block a receptor involved in pain sensitization and opioid tolerance, which partly explains why methadone works differently from other opioids.
Methadone has an unusually long duration of action. Its half-life averages about 24 hours but can range anywhere from 8 to 59 hours depending on the person. This slow clearance is what allows once-daily dosing for opioid use disorder treatment and chronic pain management.
What’s in Methadone Tablets
Methadone tablets, sold under the brand name Dolophine and various generics, have a short and simple ingredient list. Each tablet contains methadone hydrochloride plus three inactive ingredients: magnesium stearate (a lubricant that prevents the pill from sticking to manufacturing equipment), microcrystalline cellulose (a plant-based filler that gives the tablet its bulk), and pregelatinized starch (a binder that holds everything together). These tablets contain no lactose, no artificial dyes, and no preservatives.
What’s in Liquid Methadone
Liquid formulations are more complex and vary significantly between products. If you’ve seen methadone dispensed at a clinic, it was likely one of these.
Cherry-Flavored Concentrate (Methadose)
The standard Methadose oral concentrate is a red liquid sweetened with sucrose and colored with two red dyes: FD&C Red No. 40 and D&C Red No. 33. It contains artificial cherry flavoring, two paraben preservatives (methylparaben and propylparaben), and several other inactive ingredients including citric acid, propylene glycol, and sodium citrate. This is probably the most widely recognized version of liquid methadone.
Citrus-Flavored Oral Solution
A separate generic oral solution comes in an orange color with lemon flavoring. Its ingredient list looks quite different: it contains 8% alcohol, benzoic acid as a preservative, glycerin, sorbitol (a sugar alcohol sweetener), and two dyes, FD&C Red No. 40 and FD&C Yellow No. 6. This version is available in both 1 mg/mL and 2 mg/mL concentrations.
Sugar-Free Concentrate
For people who need to avoid sugar or artificial dyes, a sugar-free version of Methadose exists. It is both dye-free and unflavored, appearing as a clear liquid rather than a colored one. Its inactive ingredient list is minimal: citric acid, purified water, and sodium benzoate as the sole preservative. This formulation, made by SpecGx LLC, is a practical option for people with diabetes or dye sensitivities.
What’s in Injectable Methadone
Injectable methadone is used in hospital settings, not at outpatient clinics. It contains methadone hydrochloride dissolved in a sterile solution with sodium chloride (saline) and chlorobutanol at 0.5% as a preservative. The pH may be adjusted during manufacturing using sodium hydroxide or hydrochloric acid. The ingredient list is deliberately minimal because anything injected into the body needs to be as clean and simple as possible.
Ingredients That May Matter to You
Several ingredients across these formulations are worth flagging depending on your situation. The standard Methadose concentrate contains parabens, which some people prefer to avoid. The generic citrus oral solution contains alcohol at 8%, which could be relevant for people in recovery from alcohol use disorder or those taking medications that interact with alcohol. FD&C dyes appear in most colored liquid versions and can cause reactions in people with certain dye sensitivities. Sorbitol, present in the citrus solution, can cause digestive discomfort in some people, particularly at higher volumes.
If any of these ingredients are a concern, the sugar-free Methadose concentrate offers the cleanest formulation among the liquids, with just three inactive ingredients and no dyes, sugar, alcohol, or parabens. Tablets are similarly straightforward. Knowing exactly what’s in your specific formulation lets you have a more informed conversation about which version works best for your needs.