For allergy sufferers, Benadryl is one of the most popular over-the-counter medications on the market today. The medication, which is also called diphenhydramine, is available in both pill and liquid formulas. A topical cream is also available to treat allergic rashes. While it is an effective antihistamine, Benadryl causes extreme drowsiness in some people. It can also create a high feeling. Because of these factors, individuals may need to eliminate the substance from their system before going to work, driving a vehicle or doing other types of activities that require a high level of alertness and mental clarity. In addition, it can sometimes cause a false positive for illicit drugs. Those who use Benadryl regularly or at higher doses than recommended may also develop an addiction.
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What is Benadryl?
Benadryl is commonly found on the shelf with other allergy medicines at drug stores, grocery stores and other venues, making it an easy-to-access and effective antihistamine. Diphenhydramine is also sold as a sleeping aid in brand names like Unisom and Sominex. When the human body detects allergens, including animal hair, pollen, dust and others, it produces an allergic response through the production of histamines. A runny nose, sneezing, itchy eyes, a scratchy throat and breathing problems are common symptoms of allergies. As an antihistamine, Benadryl disrupts the allergic response and eases related symptoms. Because Benadryl has sedative properties, it can cause extreme relaxation akin to a calm high and significant drowsiness. When mixed with alcohol accidentally or intentionally, the sedative effect can be magnified.
Pharmacokinetics of Benadryl
Approximately 15 minutes after taking a dose of diphenhydramine, the user typically starts to feel the drug’s effects. The medication is fully absorbed in only 20 to 30 minutes. However, it can take up to four hours before the peak effects are felt. Keep in mind that these times are based on oral ingestion. The effects of diphenhydramine are experienced within minutes when taking the drug via an injection. For usage as a topical antihistamine for a skin rash, the effects may not be felt for up to 24 hours. The body metabolizes this medication in the liver and kidneys. Through metabolization, the substance is filtered out of the body and then excreted in the form of urine.
Half-Life of Benadryl
The half-life of a medication describes how long it usually takes for the body to eliminate half of the substance through the natural metabolic processes. The half-life of Benadryl varies considerably based on numerous factors. Overall, the half-life may be as short as 2.4 hours or as long as 9.3 hours. This means that it could take more than nine hours to eliminate half of the drug from the body. Based on this half-life range, the body may not flush out the entire dose for anywhere from 13.2 hours to 49 hours. The medication’s effects can linger well after the peak benefits are felt.
Factors Influencing Benadryl Duration
In many situations, an individual needs to know how long the drug will remain in his or her system, such as before driving a vehicle, going to work, taking a drug test and tackling other plans. Because of the large time frame, both the half-life and total time for elimination from the body, a closer look at the factors influencing the drug’s duration is essential.
One of these factors is age. Diphenhydramine is most quickly metabolized in the body by those who are between the ages of 12 and 65. Another factor that affects how long Benadryl stays in the body is hydration. The body can more efficiently metabolize the drug and fully eliminate it when the body is well-hydrated. Keep in mind that each person naturally has a different metabolic rate even when these factors have already been taken into account. Metabolism is strongly based on a person’s body mass index as well. Those with a lower BMI may metabolize the drug more quickly.
Taking more than the recommended amount of Benadryl can increase the severity of the side effects and can result in a higher risk of drug dependence and addiction. More than that, the body takes more time to metabolize higher doses. Metabolization is also affected by the presence of alcohol and other prescription and over-the-counter medications. Be aware that other substances also increase the risk of an overdose.
Because both the liver and kidneys process Benadryl in the human body, the health of these organs directly affects the metabolization processes. In some cases, such as when either or both of these organs are significantly impaired, it may not be safe to take even a small amount of diphenhydramine. In such situations, individuals should consult with a medical professional before taking Benadryl.
Detection Times
As an over-the-counter medication, it is legal to take Benadryl as directed and without a doctor’s prescription. However, this medication can sometimes result in a false-positive for PCP and benzodiazepines on a drug test. Because of this, use of the medication should always be disclosed upfront before taking a drug test. Drug tests can detect the medication in blood and urine for more than two days in some cases. It may also yield a positive result in hair tests taken weeks or more after using the drug. The specific metabolic factors, the amount of the medication taken and other factors directly affect the metabolic process and detection time.
| Aspect | Duration |
|---|---|
| Blood | Up to 24 hours |
| Urine | Up to 2-4 days |
| Hair | Several weeks or more |
Symptoms of Prolonged Presence in the Body
Benadryl commonly causes symptoms like blurry vision, sleeplessness, low blood pressure, headaches and dizziness. However, when the medication is misused, such as by taking more than recommended or by taking it for a long period of time, individuals may experience more serious symptoms. These include memory loss, a higher risk of dementia, hallucinations, seizures, blood cell level changes, problematic heart rhythm changes and others. In some instances, taking too large of a dose or taking the medication for a long period of time can enhance effects like low blood pressure and changes to heart rhythms to create a serious health issue. In addition,
Safe Usage Guidelines
For adults and children who are older than 12 years old, the recommended dosage is one or two pills every four to six hours. No more than six doses should be taken in a 24-hour period. The adult dose is 50 milligrams. Benadryl should only be taken as needed and should be discontinued once symptoms clear up. Individuals should avoid driving and operating heavy machinery until after the medication has been fully eliminated from their system. When used for allergy relief, the medication should not be taken for more than seven days in a row. As a sleep aid, it should not be taken for more than two weeks. If the medication is needed for longer than these time periods, consult with a healthcare provider.
Benadryl Withdrawal and Discontinuation
When taking Benadryl for longer than recommended, at higher dosages or in combination with alcohol or other drugs, withdrawal effects are possible. Some people may experience a recurrence of the original symptoms, or they may develop new symptoms. Some of these new withdrawal symptoms may include dizziness, sweating, headaches, anxiety, vomiting and nausea. These withdrawal symptoms could persist for up to eight weeks in some people. To discontinue use safely, consult with a doctor. Some individuals may benefit from a drug rehabilitation program if the effects are severe, such as if they are breaking an addiction to the medication.
Conclusion
Benadryl serves beneficial purposes as an antihistamine and a sleep aid, but it is possible to abuse the drug and develop an addiction. More than that, the medication may remain in the body for more than two days and can be detected by blood and urine tests for that time. Taking the medication as recommended and not in combination with other medications and alcohol are crucial. Individuals who experience harsh side effects or who feel the need to take more than recommended should seek medical advice.
