Medication Ingredients Glossary (A–Z)
About this glossary
This glossary explains common inactive ingredients (excipients) used in prescription and over-the-counter medications.
Ingredient lists can vary by product and manufacturer. To see which ingredients appear in a specific medication, use the PillParser scan tool.
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Browse common inactive ingredients (excipients) found in prescription and over-the-counter medications. Each entry explains the ingredient’s purpose and any known allergen risks.
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A | B | C | D | E | F | G |
H | I | L | M | P | S | T |
W | X | Z
A
Acacia (Gum Arabic)
Type: Binder / Stabilizer
Purpose: Helps tablets hold together and improves texture in liquids.
Allergy Risk: Rare; may affect those with tree gum sensitivities.
Also Known As: Gum arabic, E414.
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Aluminum Lake Dyes
Type: Colorant
Purpose: Provides stable tablet/capsule coloring.
Allergy Risk: Generally low; dye sensitivities possible.
Also Known As: Lake pigments (e.g., FD&C Red 40 Aluminum Lake).
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Ammonium Hydroxide
Type: pH Adjuster / Processing Aid
Purpose: Helps adjust acidity (pH) during manufacturing; may be used in small amounts in coatings or processing.
Allergy Risk: Low; may irritate sensitive tissues if exposure occurs, but amounts in finished products are typically minimal.
Also Known As: Aqueous ammonia, ammonia solution.
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Aspartame
Type: Sweetener
Purpose: Improves taste in chewables, ODTs, and liquids.
Allergy Risk: Contains phenylalanine; avoid in PKU.
Also Known As: E951.
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B
Benzalkonium Chloride
Type: Preservative
Purpose: Prevents microbial growth in ophthalmic, nasal, and topical products.
Allergy Risk: Can irritate eyes/skin in sensitive users.
Also Known As: BAK.
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Benzyl Alcohol
Type: Preservative / Solvent
Purpose: Antimicrobial; improves solubility in liquids.
Allergy Risk: May cause irritation or sensitivity reactions.
Also Known As: Phenylmethanol.
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Butylated Hydroxyanisole (BHA)
Type: Antioxidant
Purpose: Protects ingredients from oxidation.
Allergy Risk: Rare sensitivity possible.
Also Known As: E320.
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Butylated Hydroxytoluene (BHT)
Type: Antioxidant
Purpose: Stabilizes fats/oils in formulations.
Allergy Risk: Rare sensitivity possible.
Also Known As: E321.
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C
Calcium Carbonate
Type: Filler / Antacid
Purpose: Adds tablet bulk; sometimes neutralizes acid.
Allergy Risk: Low; mineral source.
Also Known As: E170.
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Calcium Phosphate
Type: Filler / Buffer
Purpose: Adds tablet bulk and hardness; may help stabilize formulation pH.
Allergy Risk: Low; mineral source.
Also Known As: Tricalcium phosphate (TCP), calcium phosphate tribasic, E341.
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Carrageenan
Type: Thickener / Stabilizer
Purpose: Helps thicken and stabilize liquids, suspensions, and some gel-like formulations.
Allergy Risk: Low; seaweed-derived. May cause GI irritation in sensitive individuals.
Also Known As: Irish moss extract, E407.
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Carnauba Wax
Type: Glidant / Polish
Purpose: Tablet coating for shine and protection.
Allergy Risk: Low.
Also Known As: E903.
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Cellulose (Microcrystalline)
Type: Filler / Binder
Purpose: Provides tablet structure and compressibility.
Allergy Risk: Low; plant-derived.
Also Known As: MCC, Avicel, E460.
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Corn Starch
Type: Binder / Disintegrant
Purpose: Helps tablets hold together during manufacturing and allows them to break apart properly after ingestion.
Allergy Risk: Low; derived from corn.
Also Known As: Maize starch, starch, pregelatinized starch, modified corn starch.
Croscarmellose Sodium
Type: Disintegrant
Purpose: Helps tablets break apart for absorption.
Allergy Risk: Low.
Also Known As: Cross-linked carboxymethylcellulose.
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Citric Acid
Type: Acidulant / Buffer
Purpose: Adjusts pH and improves flavor/stability.
Allergy Risk: Low; may irritate in high amounts.
Also Known As: E330.
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D
Dextrose (Glucose)
Type: Sweetener / Filler
Purpose: Improves taste; adds tablet bulk.
Allergy Risk: Corn-derived; consider corn allergy.
Also Known As: D-glucose.
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Dicalcium Phosphate
Type: Filler
Purpose: Provides tablet hardness and bulk.
Allergy Risk: Low.
Also Known As: DCP.
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Dyes (Color Additives)
Type: Colorant
Purpose: Adds color to tablets or capsules for identification, branding, or dosage differentiation.
Allergy Risk: Generally low; sensitivities may occur in some individuals.
Also Known As: FD&C dyes, aluminum lake dyes, color additives (e.g., FD&C Red 40, FD&C Yellow 5).
E
Ethylcellulose
Type: Coating Polymer
Purpose: Controls release; taste-masking.
Allergy Risk: Low.
Also Known As: EC.
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Ethanol (Alcohol)
Type: Solvent
Purpose: Dissolves actives in liquids and sprays.
Allergy Risk: May irritate; avoid with alcohol intolerance.
Also Known As: Ethyl alcohol.
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F
FD&C Blue No. 1
Type: Colorant
Purpose: Colors tablets/capsules and liquids.
Allergy Risk: Dye sensitivities possible.
Also Known As: Brilliant Blue FCF, E133.
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FD&C Red No. 40
Type: Colorant
Purpose: Provides red coloring.
Allergy Risk: Sensitivity possible in some users.
Also Known As: Allura Red AC, E129.
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FD&C Yellow No. 5 (Tartrazine)
Type: Colorant
Purpose: Yellow coloring for tablets/capsules.
Allergy Risk: May trigger reactions in aspirin-sensitive individuals.
Also Known As: Tartrazine, E102.
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Ferric Oxide (Red / Yellow / Black)
Type: Colorant
Purpose: Provides stable red, yellow, or black coloring in tablet/capsule coatings for identification and appearance.
Allergy Risk: Low; mineral pigment. Sensitivities are uncommon.
Also Known As: Iron oxides, ferric oxides, CI pigments (varies by color).
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Flavorings (Natural or Artificial)
Type: Flavor
Purpose: Improves palatability of chewables and liquids.
Allergy Risk: Source-dependent; check label (e.g., citrus, mint).
Also Known As: Flavor, natural flavors.
G
Gelatin
Type: Capsule Material / Binder
Purpose: Forms softgel/hard capsule shells.
Allergy Risk: Animal-derived (bovine/porcine); avoid if allergic or for dietary reasons.
Also Known As: Hydrolyzed collagen.
Glycerin
Type: Humectant / Plasticizer
Purpose: Retains moisture; softens capsules.
Allergy Risk: Low; can cause GI upset in high amounts.
Also Known As: Glycerol, E422.
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Guar Gum
Type: Thickener / Stabilizer
Purpose: Increases viscosity in liquids and suspensions.
Allergy Risk: Rare; fiber-related GI effects possible.
Also Known As: E412.
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H
Hypromellose (HPMC)
Type: Binder / Film Former / Capsule Material
Purpose: Used in controlled release and vegetarian capsules.
Allergy Risk: Low; cellulose-derived.
Also Known As: Hydroxypropyl methylcellulose, E464.
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Hydroxypropyl Cellulose (HPC)
Type: Binder / Disintegrant
Purpose: Improves tablet cohesion and breakup.
Allergy Risk: Low.
Also Known As: HPC, E463.
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I
Iron Oxides
Type: Colorant
Purpose: Provides red/yellow/brown tablet color.
Allergy Risk: Low; mineral pigments.
Also Known As: Ferric oxides (red, yellow, black).
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Isomalt
Type: Sugar Alcohol Sweetener / Filler
Purpose: Taste-masking in chewables and ODTs.
Allergy Risk: Can cause GI discomfort in high amounts.
Also Known As: E953.
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L
Lactose
Type: Filler / Binder
Purpose: Adds volume and improves tablet flow.
Allergy Risk: Milk-derived; avoid with milk protein allergy or lactose intolerance.
Also Known As: Lactose monohydrate, anhydrous lactose.
Lecithin (Soy)
Type: Emulsifier
Purpose: Stabilizes softgels and suspensions.
Allergy Risk: Soy-derived; avoid if allergic to soy.
Also Known As: Phosphatidylcholine.
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M
Magnesium Stearate
Type: Lubricant
Purpose: Prevents sticking during tablet compression.
Allergy Risk: Typically low; may be from vegetable or animal fat sources.
Also Known As: Stearic acid magnesium salt.
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Mannitol
Type: Sweetener / Filler
Purpose: Improves mouthfeel of chewables/ODTs.
Allergy Risk: May cause GI upset at higher doses.
Also Known As: E421.
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Maltodextrin
Type: Filler / Stabilizer
Purpose: Adds bulk; improves powder flow.
Allergy Risk: Often corn-derived; consider corn allergy.
Also Known As: Hydrolyzed starch.
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Methylparaben
Type: Preservative
Purpose: Inhibits microbial growth in liquids and topicals.
Allergy Risk: Possible contact sensitivity in some users.
Also Known As: MePar, E218.
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Mineral Oil
Type: Lubricant / Emollient
Purpose: Aids manufacturing; softens topicals.
Allergy Risk: Low; petroleum-derived.
Also Known As: Paraffinum liquidum.
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P
Polyethylene Glycol (PEG)
Type: Solvent / Plasticizer / Ointment Base
Purpose: Softens capsules; improves solubility and coatings.
Allergy Risk: Rare PEG sensitivity reported.
Also Known As: Macrogol (e.g., PEG 400, PEG 3350).
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Polyethylene Oxide
Type: Release-Controlling Polymer / Binder
Purpose: Helps control how a medication dissolves (often used in extended-release tablets) and can improve tablet structure.
Allergy Risk: Low; polymer-related sensitivities are uncommon.
Also Known As: PEO, polyethylene polymer (grade varies).
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Polysorbate 80
Type: Emulsifier / Solubilizer
Purpose: Helps mix oil- and water-based ingredients.
Allergy Risk: Rare hypersensitivity possible.
Also Known As: Tween 80, E433.
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Potassium Sorbate
Type: Preservative
Purpose: Helps prevent mold and yeast growth in liquids, suspensions, and some oral/topical products.
Allergy Risk: Low; may cause irritation or sensitivity in some individuals.
Also Known As: E202.
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Povidone (PVP)
Type: Binder / Solubilizer
Purpose: Improves tablet strength and dissolution.
Allergy Risk: Low; rare PVP sensitivity.
Also Known As: Polyvinylpyrrolidone.
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Polyvinyl Alcohol (PVA)
Type: Film Former / Coating Polymer
Purpose: Used in tablet film coatings to improve stability, appearance, and swallowing.
Allergy Risk: Low; rare sensitivity possible.
Also Known As: PVA, poly(ethylene vinyl alcohol) (not the same as EVOH), vinyl alcohol polymer.
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Propylene Glycol
Type: Solvent / Humectant
Purpose: Improves solubility and moisture retention.
Allergy Risk: May cause irritation in sensitive users.
Also Known As: PG, E1520.
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Propylparaben
Type: Preservative
Purpose: Helps prevent microbial growth in liquids and some topical formulations.
Allergy Risk: Possible contact sensitivity in some users.
Also Known As: ProPar, E216.
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Pregelatinized Starch (Corn)
Type: Binder / Disintegrant
Purpose: Aids tablet formation and breakup.
Allergy Risk: Corn-derived; consider corn allergy.
Also Known As: Starch pregelatinized.
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S
Shellac (Pharmaceutical Glaze)
Type: Coating / Glazing Agent
Purpose: Provides a protective shine and moisture barrier on tablets/capsules; helps improve swallowability.
Allergy Risk: Low, but insect-derived; avoid if sensitive or for dietary/ethical reasons.
Also Known As: Pharmaceutical glaze, confectioner’s glaze, lac resin, E904.
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Silicon Dioxide
Type: Anti-caking Agent
Purpose: Keeps powders free-flowing during manufacturing.
Allergy Risk: Generally recognized as safe; low risk.
Also Known As: Colloidal silica, E551.
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Sodium Alginate
Type: Thickener / Stabilizer
Purpose: Helps thicken liquids and stabilize suspensions; may also be used to control texture in gels.
Allergy Risk: Low; seaweed-derived.
Also Known As: Algin, alginic acid sodium salt, E401.
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Sodium Benzoate
Type: Preservative
Purpose: Prevents microbial growth in liquids.
Allergy Risk: Rare sensitivity possible.
Also Known As: E211.
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Sodium Citrate
Type: Buffer / Stabilizer
Purpose: Helps control acidity (pH) and improve stability in solutions, liquids, and some tablets.
Allergy Risk: Low; may irritate sensitive stomachs in some individuals.
Also Known As: Trisodium citrate, E331.
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Sodium Hydroxide
Type: pH Adjuster / Processing Aid
Purpose: Used to adjust pH during manufacturing (especially in liquids and injectables) to stabilize the formulation.
Allergy Risk: Low in finished products; caustic in concentrated form.
Also Known As: Lye, caustic soda.
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Sodium Metabisulfite
Type: Preservative / Antioxidant
Purpose: Prevents oxidation and helps maintain stability (common in some injectables and solutions).
Allergy Risk: Sulfite sensitivity possible; may trigger reactions in susceptible individuals.
Also Known As: Sodium pyrosulfite, E223.
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Sodium Phosphate (Monobasic / Dibasic)
Type: Buffer / Stabilizer
Purpose: Helps control pH and improve stability in liquids, eye drops, and some oral formulations.
Allergy Risk: Low; mineral salts.
Also Known As: Monosodium phosphate, disodium phosphate, phosphate salts.
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Sodium Saccharin
Type: Sweetener
Purpose: Improves taste in chewables, liquids, and some dissolvable/ODT formulations.
Allergy Risk: Low; sensitivity is uncommon.
Also Known As: Saccharin sodium, E954.
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Sodium Starch Glycolate
Type: Superdisintegrant
Purpose: Rapid tablet breakup for absorption.
Allergy Risk: Often potato-derived; check source.
Also Known As: SSG.
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Sorbitol
Type: Sweetener / Humectant
Purpose: Improves taste and moisture retention.
Allergy Risk: Can cause GI upset at higher doses.
Also Known As: E420.
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Sodium Lauryl Sulfate (SLS)
Type: Surfactant
Purpose: Aids wetting and tablet disintegration; enhances dissolution.
Allergy Risk: May irritate skin/mucosa in sensitive users.
Also Known As: Sodium dodecyl sulfate.
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T
Talc
Type: Glidant / Anti-caking Agent
Purpose: Improves powder flow; prevents sticking.
Allergy Risk: Low; inhalation risk if misused.
Also Known As: Magnesium silicate, E553b.
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Titanium Dioxide
Type: Opacifier / Colorant
Purpose: White coating; protects from light.
Allergy Risk: Generally low; regulatory review ongoing in some regions.
Also Known As: TiO₂, E171.
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W
Water (Purified)
Type: Solvent / Vehicle
Purpose: Carries dissolved ingredients in liquids and injectables.
Allergy Risk: None typical; purity standards apply.
Also Known As: Purified water, USP.
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Wheat Starch
Type: Binder / Disintegrant
Purpose: Aids tablet cohesion and breakup.
Allergy Risk: Contains gluten; avoid with wheat/gluten allergy or celiac disease.
Also Known As: Triticum vulgare starch.
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X
Xanthan Gum
Type: Thickener / Stabilizer
Purpose: Increases viscosity for suspensions and gels.
Allergy Risk: Low; may cause GI gas in some users.
Also Known As: E415.
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Z
Zinc Stearate
Type: Lubricant
Purpose: Reduces friction during tablet compression.
Allergy Risk: Low.
Also Known As: Stearic acid zinc salt.
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Medications with the same active ingredient can contain different inactive ingredients depending on the manufacturer and formulation.
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