How Long Does Benadryl Stay in Your System?

Every individual living most of all on this planet has heard the name of Benadryl. We are not over exaggerating, but this is a fact. However, there are certain myths regarding the use of Benadryl as a medicine and as a medicine.

Let’s now take a look at the different issues related to Benadryl – which is famously known as the most widely used cough syrup.

History of Benadryl

Benadryl is considered a brand name for a variety of drugs belonging to the over-the-counter (OTC) clinic. Various chemical ingredients like diphenhydramine and others are the main constituents of the OTC class.

They are a type of antihistamines. The evidence indicates that Johnson & Johnson has acquired the “Benadryl” brand from its previous owner (Pfizer) and is still the owner of Johnson & Johnson.

Given the past and current scenarios, Benadryl is the only and the most popular antihistamine to have come so far.

Cough syrup Benadryl is manufactured in a variety of formulations by its manufacturers. Its basic features include the treatment of a wide variety of diseases.

It is intended to treat a wide range of clinical conditions. These conditions mainly include clinical symptoms such as a cough, allergies, insomnia, motion sickness, nausea, and itching.

It is believed that the diphenhydramine content that is present in Benadryl has certain therapeutic effects with histamine H1 antagonist receptors. It is also known to produce an inhibition effect of the sodium channels in (intracellular) cells.

About eight out of ten people are reported to have used Benadryl at least once in their lifetime. Benadryl is indicated as the most commonly used medication for all allergic conditions. It is also considered a safe medicine when consumed in appropriate amounts.

However, there are chances that the drug could lead to serious side effects. Therefore, it is a wise choice to seek advice before consuming Benadryl!

Let’s see now the different effects, side effects and effects on different age groups Benadryl could lead to.

What is Benadryl?

It is a good idea first to have some basic details of this medicine. As noted above this drug is commonly known as Benadryl. However, it is clinically a variant of diphenhydramine. Although this utility of Benadryl is rarely taken into consideration, Benadryl is known to have positive effects in the treatment of Parkinson’s disease.

To have an exact knowledge of how long Benadryl will remain in your body, it is very necessary to have a better idea of the life cycle of the drugs.

The life cycle and structure of Benadryl varies and depends on certain factors. These mainly include age, internal metabolism, clinical history, psychological state, etc.

Let’s see how much time the drug stays inside the human body by the age of the person.

  • Children – about 7 hours
  • Adults – approximately 12 hours
  • The elderly – about 17 hours

It should be noted that Benadryl’s life cycle plays a vital role in determining how long the drug takes to leave your body. Given the general statistic is the time for elimination of Benadryl from the human body by each belonging to these categories is as follows:

  • Children – 14 hours
  • Adults – 24 hours
  • Seniors – 34 hours

Given the value above is it will take about a day for Benadryl to leave your body entirely.

How long does Benadryl stays in your system?

Variables that affect how long Benadryl stays in your system

We understood that there is a significant amount of interindividual variation in the elimination time of this drug.

These interindividual differences in the elimination of this drug are known to be the result of various factors.

These consist mainly of a frequency of ingestion, the age of the person, dosage, liver function and co-administration of other drugs. These are the factors that are necessary to be taken into consideration when considering the amount of time Benadryl stays in your body after stopping consuming it.

1. Age (Old vs. Young)

Research indicates that seniors (over 65 years of age) are likely to retain Benadryl in their body for a longer duration compared to children and young adults. Based on this information, it can be concluded that it is approximately 3.1 days for the complete elimination of diphenhydramine from the body systems of the elderly.

Tell statistics that nearly 2.11 days are required by young adults for the complete elimination of Benadryl and only 1.24 days by children.

2. Liver function

The clinical study indicates that certain enzymes present in our liver metabolizes the content present in diphenhydramine Benadryl.

Thus, elimination of Benadryl materials is affected due to liver failure. If the liver is damaged in any way, the life span of Benadryl in the human body is greatly affected.

It can take about 4 to 6 for the complete removal of all Benadryl content from the human body if you are suffering from or having severe liver failure.

Research shows that the increase in complete elimination time is more in cirrhotic patients. It is mainly because of the increase in bilirubin content.

In adults with normal hepatic function, complete elimination of Benadryl occurs in only about 2 days.

3. Dosage (low compared to high)

This is one of the main factors to consider while checking how long Benadryl will stay in your body. The dose of Benadryl is given according to the age of the individual. It is as follows:

  • Children – 0 mg to 25 mg
  • Adults and the elderly – 25 mg to 50 mg

So, it can be easily noted that the higher the dose amount; the greater the duration for which the drug will reside in your body. However, there are other factors that affect the length of time.

Frequency (Single vs. multi-dose)

How often do you use Benadryl?

The answer to this question will surely affect the duration for which the drug resides inside the human body. It makes sense to say that a person who takes a single dose of medication a day is bound to eliminate the drug at a faster rate.

On the contrary, the person who takes it several times a day will take longer to eliminate it. This is mainly due to the logic that a user taking a single dose user is likely to have less amount of Benadryl accumulated in his body.

5. Concurrent drug administration (CYP2D6)

If you are taking other medicines with Benadryl, then it is possible that there may be an increase or decrease in the time needed for complete elimination.

Clinically, there is evidence that the enzyme cytochrome P450 (CYP2D6) affects diphenhydramine, which is the active ingredient in Benadryl.

Thus, taking into consideration the other medications that the person ingests becomes too important.

Various individual factors

  • Body Mass: As a general rule, it is a fact that the person is more massive, the more the medication will be removed from his body.
  • Genetics: This is an important factor affecting the amount for which Benadryl remains in an individual’s body. There is no concrete explanation for the same.
  • Hydration: It refers to some fluids present in the body. The higher the fluid content, the faster the urine is produced. Benadryl is eliminated out of the body in the form of urine.
  • The metabolic rate: a person ‘s basal metabolic rate is having a great influence on the time required for the elimination of all drugs, including Benadryl. It is a general scenario that a person with a large number of BMR tends to burn more energy as well as fat. This greatly affects the rate at which drugs are eliminated from the human body
  • Renal function: Medically there is evidence that people with liver problems have a low drug diffusion rate.
  • Urinary PH: People with high urinary pH are likely to need more time for complete elimination of Benadryl. High pH leads to increased acidity, which affects the body’s metabolism.

Side effects of Benadryl

As with all medications, there are side effects of Benadryl as well. These side effects range from mild to moderate and also vary from person to person.

  • Dizziness (vertigo)
  • A headache
  • dry oral and nasal cavities
  • A feeling of needing to urinate frequently
  • Drowsiness
  • Tired
  • Dysuria (difficulty urinating)
  • Some users may experience paranoia and anxiety when taking Benadryl over long periods.
  • Drugs interactions
  • itching
  • Nausea
  • Lack of sleep
  • Swelling of the internal parts of the body
  • hot impulses

It is crucial and very important to know that Benadryl consumption with Xanax is very dangerous. Xanax contains an ingredient that should never be consumed with Benadryl. It increases the risk of antihistamine overdose. So, it is very important to consult a doctor before taking Benadryl

How to delete Benadryl from your system

a. Urinary pH: It is possible to change the urinary pH using certain additives. It helps in the rapid elimination of Benadryl from the body.

b. Activated charcoal: This is a very good option if you have consumed a lot of Benadryl and wanted to take it out of your body. Activated carbon is having an opposite charge and tends to attract Benadryl molecules and eliminated from the body.

c. Calcium-D-Glucarate : This supplement is very useful for facilitating the elimination of various toxins like Benadryl by our kidneys.

Re. Hydration /Exercise: Drinking plenty of water, makes a person urinate frequently. It facilitates the elimination of Benadryl from the body.


Thus, we can conclude with the following points: –

  • It is wrong to say that Benadryl is not excellent or conducive to human health.
  • It is really necessary and a wise choice to consult a doctor before deciding on the dose of Benadryl to consume.
  • Benadryl in large quantities will surely have negative effects in one form or the other.