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.
Jump to:
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.
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).
Aspartame
Type: Sweetener
Purpose: Improves taste in chewables, ODTs, and liquids.
Allergy Risk: Contains phenylalanine; avoid in PKU.
Also Known As: E951.
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.
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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Carnauba Wax
Type: Glidant / Polish
Purpose: Tablet coating for shine and protection.
Allergy Risk: Low.
Also Known As: E903.
Cellulose (Microcrystalline)
Type: Filler / Binder
Purpose: Provides tablet structure and compressibility.
Allergy Risk: Low; plant-derived.
Also Known As: MCC, Avicel, E460.
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.
Citric Acid
Type: Acidulant / Buffer
Purpose: Adjusts pH and improves flavor/stability.
Allergy Risk: Low; may irritate in high amounts.
Also Known As: E330.
D
Dextrose (Glucose)
Type: Sweetener / Filler
Purpose: Improves taste; adds tablet bulk.
Allergy Risk: Corn-derived; consider corn allergy.
Also Known As: D-glucose.
Dicalcium Phosphate
Type: Filler
Purpose: Provides tablet hardness and bulk.
Allergy Risk: Low.
Also Known As: DCP.
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.
Ethanol (Alcohol)
Type: Solvent
Purpose: Dissolves actives in liquids and sprays.
Allergy Risk: May irritate; avoid with alcohol intolerance.
Also Known As: Ethyl alcohol.
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.
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.
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.
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.
Guar Gum
Type: Thickener / Stabilizer
Purpose: Increases viscosity in liquids and suspensions.
Allergy Risk: Rare; fiber-related GI effects possible.
Also Known As: E412.
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.
Hydroxypropyl Cellulose (HPC)
Type: Binder / Disintegrant
Purpose: Improves tablet cohesion and breakup.
Allergy Risk: Low.
Also Known As: HPC, E463.
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).
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.
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.
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.
Mannitol
Type: Sweetener / Filler
Purpose: Improves mouthfeel of chewables/ODTs.
Allergy Risk: May cause GI upset at higher doses.
Also Known As: E421.
Maltodextrin
Type: Filler / Stabilizer
Purpose: Adds bulk; improves powder flow.
Allergy Risk: Often corn-derived; consider corn allergy.
Also Known As: Hydrolyzed starch.
Methylparaben
Type: Preservative
Purpose: Inhibits microbial growth in liquids and topicals.
Allergy Risk: Possible contact sensitivity in some users.
Also Known As: MePar, E218.
Mineral Oil
Type: Lubricant / Emollient
Purpose: Aids manufacturing; softens topicals.
Allergy Risk: Low; petroleum-derived.
Also Known As: Paraffinum liquidum.
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).
Polysorbate 80
Type: Emulsifier / Solubilizer
Purpose: Helps mix oil- and water-based ingredients.
Allergy Risk: Rare hypersensitivity possible.
Also Known As: Tween 80, E433.
Povidone (PVP)
Type: Binder / Solubilizer
Purpose: Improves tablet strength and dissolution.
Allergy Risk: Low; rare PVP sensitivity.
Also Known As: Polyvinylpyrrolidone.
Propylene Glycol
Type: Solvent / Humectant
Purpose: Improves solubility and moisture retention.
Allergy Risk: May cause irritation in sensitive users.
Also Known As: PG, E1520.
Pregelatinized Starch (Corn)
Type: Binder / Disintegrant
Purpose: Aids tablet formation and breakup.
Allergy Risk: Corn-derived; consider corn allergy.
Also Known As: Starch pregelatinized.
S
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.
Sodium Benzoate
Type: Preservative
Purpose: Prevents microbial growth in liquids.
Allergy Risk: Rare sensitivity possible.
Also Known As: E211.
Sodium Starch Glycolate
Type: Superdisintegrant
Purpose: Rapid tablet breakup for absorption.
Allergy Risk: Often potato-derived; check source.
Also Known As: SSG.
Sorbitol
Type: Sweetener / Humectant
Purpose: Improves taste and moisture retention.
Allergy Risk: Can cause GI upset at higher doses.
Also Known As: E420.
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.
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.
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.
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.
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.
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.
Z
Zinc Stearate
Type: Lubricant
Purpose: Reduces friction during tablet compression.
Allergy Risk: Low.
Also Known As: Stearic acid zinc salt.