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What Are Benadryl’s Inactive Ingredients?

Understanding What's In Benadryl

Dr. Lyssa Logue Profile Photo

Written by Dr. Lyssa Logue on October 6, 2021

Medically reviewed by Camille Freking, MS Pharmacology

Benadryl is a popular medication brand that is known for producing medications that are designed to treat acute allergy symptoms. Perhaps most recognized by their distinctive bright pink tablets, Benadryl makes formulas for both children and adults who are suffering from allergy symptoms.

If you’re considering using medicine to help control your allergy symptoms, you might be wondering “what are Benadryl’s inactive ingredients?”

What is the difference between active and inactive ingredients?

All medications contain both active and inactive ingredients. Under 21 Code of Federal Regulations (CFR) 210.3, Current Good Manufacturing Practice in Manufacturing, Processing, Packing or Holding of Drugs, Part (b)(7), an active ingredient is defined as any component of a drug product that is intended to furnish pharmacological activity or other direct effect in the diagnosis, cure, mitigation, treatment, or prevention of disease, or to affect the structure or any function of the body of humans or animals.

Put more simply, active ingredients are the parts of your medication that are treating your symptoms. If you have a sore throat, the active ingredient would be the ingredient that reduces the pain associated with your condition.

Inactive ingredients are defined by 21 CFR 210.3(b)(8) as any component of a drug product other than the active ingredient. Nearly three quarters of most medications are made up of inactive ingredients, which heavily influence how a medication looks, tastes, and feels.

Harvard Medical School reports that the average medication contains approximately nine inactive ingredients. Inactive ingredients serve many purposes in medication, including:

  • Binding the ingredients together to give the medicine a cohesive shape
  • Masking the bitter taste of some medications to make them easier to swallow
  • Preserving the medication by preventing the growth of bacteria and fungi
  • Preventing a medication from being dissolved
  • Helping the body to absorb the drug more easily by combining with an easily digestible substance like a fatty acid

What are Benadryl’s active ingredients?

When manufactured for adults, Benadryl is produced in three different formulas: Benadryl Allergy ULTRATAB Tablets, Benadryl Allergy Dye-Free LIQUI-GELS, and Benadryl Allergy Plus Congestion.

Of these formulas, Benadryl Allergy ULTRATAB Tablets and Benadryl Allergy Plus Congestion are produced as tablets, while Benadryl Allergy Dye-Free LIQUI-GELS are produced as liquid-free capsules.

Because the Benadryl Allergy ULTRATAB Tablets are the formula with which most people are familiar, this article describes the active and inactive ingredients in that particular formula. Benadryl Allergy ULTRATAB Tablets contain 25 mg of diphenhydramine HCl, the only active ingredient, in each tablet. Adults are directed to take one to two tablets every four to six hours to help control allergy symptoms.

Diphenhydramine HCl is a type of antihistamine that is used to relieve symptoms caused by hay fever (allergic rhinitis), allergies, or the common cold.

The medication can help to relieve symptoms like runny nose, sneezing, congestion, and eyes that are red, itchy, irritated, and watery.

Benadryl Allergy ULTRATAB Tablets are intended to treat symptoms of allergies and are most commonly used to relieve symptoms associated with acute seasonal allergies.

What are Benadryl’s inactive ingredients?

Benadryl tablets contain the following inactive ingredients: carnauba wax, croscarmellose sodium, D&C red no. 27 aluminum lake, dibasic calcium phosphate, hypromellose, magnesium stearate, microcrystalline cellulose, polyethylene glycol, polysorbate 80, titanium dioxide.

Carnauba wax is a coating that consists primarily of fatty acid esters that create a slippery surface. This type of wax is most commonly used as an inactive ingredient for the purpose of making it easier to swallow tablets.

Croscarmellose sodium is a type of salt that forms a chain of cellulose instead of creating short, individual fibers. This substance is commonly included in many different types of pharmaceutical tablets because it helps the tablets to rapidly disintegrate in the stomach, improving the speed at which the medication is absorbed by the body.

D&C red no. 27 aluminum lake is a type of synthetic dye that is commonly used in cosmetics and pharmaceutical products. Lake dyes are formed by causing a reaction between straight dyes, such as D&C red no. 27, and a type of salt, such as aluminum. This inactive ingredient is used to provide coloring to the Benadryl Allergy ULTRATAB Tablets.

Dibasic calcium phosphate is an inactive ingredient that is classified as a diluent and is found in the form of a salt. Diluent ingredients are commonly used as inactive ingredients because they help to make the product large enough to swallow and handle and make the medication more stable. Without ingredients like dibasic calcium phosphate, medications like Benadryl would be too small to handle easily.

Hypromellose is considered the most commonly used cellulose and is used to provide for the release of an active ingredient in a controlled manner to prolong its therapeutic effect by increasing the length of time that it takes for the medication to completely release. While it is important that the medication start working quickly, it also needs to last long enough to provide the patient with consistent relief.

Magnesium stearate is a common inactive ingredient that is found in many types of medication capsules and tablets. This ingredient is classified as a flow agent and works by preventing the individual ingredients in a capsule or tablet from sticking to each other or to the machine that is used to create the medication. Magnesium stearate also helps to improve the consistency of medication capsules and delay the breakdown and absorption of the active ingredients, allowing them to be absorbed properly.

Microcrystalline cellulose is a type of cellulose that is classified as an excipient and is used to make tablets like Benadryl hard but easily dissolvable.

Polyethylene glycol has many different applications as an inactive ingredient in the pharmaceutical industry, including as a solvent, surfactant, plasticizer, and tablet and capsule lubricant. Ingredients like polyethylene glycol make tablets like Benadryl easier for patients to swallow.

Polysorbate 80 is a common solubilizing agent and excipient that has a variety of applications in the pharmaceutical industry. In tablets, polysorbate 80 is used as an excipient, meaning it helps to stabilize the medication to help ensure that it is properly absorbed.

Titanium dioxide is a naturally occurring mineral that is commonly used in medications as a pigment for the coatings on tablets like Benadryl Allergy ULTRATAB Tablets.

Are inactive ingredients associated with any risks?

Regardless of whether you use a prescription drug or an over the counter medication, nearly every medication contains certain inactive ingredients that help to improve the appearance, taste, color, absorption rate, and other qualities of the drug.

Most people pay attention to the types of active ingredients that are included in each medication, but inactive ingredients can also cause adverse effects, particularly in individuals who have allergies and food sensitivities.

Two of the most common risks associated with inactive ingredients in general include allergic reactions and digestive distress due to intolerances.

Allergic reactions

People with allergies to certain inactive ingredients could experience a life threatening allergic reaction called anaphylaxis if they consume a medication that contains their known allergen.

Although allergic reactions are rare when considered in the context of the general population, at least 38 different inactive ingredients have been identified as potential allergens that are commonly included in medications, and approximately 93 percent of medications included as part of one study contained at least one potential allergen.

Anaphylaxis can cause trouble breathing and can be fatal, while more mild allergic reactions can cause skin irritation, such as itching or hives.

Inactive ingredients that are known to act as allergens include dyes like sunset yellow FCF allura red, and brilliant blue; foods like cornstarch, peanut oil, gluten, lactose, and wheat starch; and sweeteners like mannitol, saccharin, aspartame, and sucrose.

Digestive distress

Some inactive ingredients can cause digestive distress in people who are sensitive to the ingredients but are not fully allergic to them. The types of inactive ingredients that most commonly trigger digestive distress are often classified as FODMAPs, an acronym that stands for fermentable oligosaccharides, disaccharides, monosaccharides, and polyols.

Ingredients that fall into these categories are made up of sugars that are hard for the body to digest and are known to cause symptoms like gas, bloating, and diarrhea. Studies have shown that approximately 55 percent of all oral medications include at least one FODMAP, with artificial sweeteners being a common culprit.

The risk of experiencing adverse effects from inactive ingredients increases as you increase the number of medications that you take. Different medications have different inactive ingredients that can compound on each other or interact to change the frequency and severity of the side effects you experience.


Benadryl Allergy ULTRATAB Tablets contain 25 mg of diphenhydramine HCl per tablet as its active ingredient. The medication also contains the following inactive ingredients: carnauba wax, croscarmellose sodium, D&C red no. 27 aluminum lake, dibasic calcium phosphate, hypromellose, magnesium stearate, microcrystalline cellulose, polyethylene glycol, polysorbate 80, titanium dioxide.

Inactive ingredients are found in all types of prescription drugs and over the counter medications but can cause allergic reactions or digestive distress in some people.