Medication Ingredients Glossary (A–Z)

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.

Butylated Hydroxyanisole (BHA)

Type: Antioxidant
Purpose: Protects ingredients from oxidation.
Allergy Risk: Rare sensitivity possible.
Also Known As: E320.

Butylated Hydroxytoluene (BHT)

Type: Antioxidant
Purpose: Stabilizes fats/oils in formulations.
Allergy Risk: Rare sensitivity possible.
Also Known As: E321.

C

Calcium Carbonate

Type: Filler / Antacid
Purpose: Adds tablet bulk; sometimes neutralizes acid.
Allergy Risk: Low; mineral source.
Also Known As: E170.

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.

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.

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.

Understanding Labels