How Long Does Benadryl Stay in Your System?

If you have experienced itching from allergies, you have probably taken Benadryl before. Benadryl is an over-the-counter allergy medication that contains diphenhydramine. It can treat hay fever, allergies, cold symptoms, and help you sleep.

While Benadryl is not considered a drug of abuse, it is possible to misuse it. Some people take large doses of diphenhydramine to experience mind-altering effects. They might also mix it with alcohol to experience a more intense high.

If you abuse Benadryl, you might be wondering how long it stays in your system. For adults, the half-life of diphenhydramine is about 9 hours.[1] In other words, Benadryl can take up to 45 hours to leave your system.

That said, drug tests can detect Benadryl for a longer period because it leaves behind metabolites in your blood, urine, saliva, and hair. For example, Benadryl can be detected in urine for 2 to 4 days after your last dose.

In this article, you will learn:

• What is Benadryl?
• What is the half-life of Benadryl?
• What factors affect how long Benadryl stays in your system?
• How long can drug tests detect Benadryl?

What is Benadryl (Diphenhydramine)?

Benadryl is an over-the-counter antihistamine used to manage allergic reactions. Because of its sedating effects, it can also be used as an occasional sleep aid. While Benadryl is effective in relieving allergy symptoms, it can cause some side effects.

The side effects of diphenhydramine include:[2]

• Dry mouth, nose, and throat
• Dizziness and drowsiness
• Nausea and vomiting
• Loss of appetite
• Constipation
• Increased congestion in the chest
• Headaches
• Muscle weakness
• Excitement or nervousness

While diphenhydramine is a relatively safe medication, it is possible to abuse it. If you are taking large doses of Benadryl to get high, you are at risk of experiencing adverse and potentially life-threatening effects. Taking too much could result in low blood pressure, slowed breathing, and respiratory depression.

What is the Half-Life of Benadryl?

Benadryl begins working in about 30 minutes after you take it. The effects will last anywhere between 4 to 6 hours.

To understand how long Benadryl stays in your system, you need to know what a drug’s half-life is. A half-life explains how long it takes your body to eliminate half of a dose. It can take 4 to 5 half-lives for a drug to be removed from your system.

The half-life of Benadryl for adults is about 9 hours.[1] in other words, it can take 45 hours to completely leave your system. If you are addicted to Benadryl, this is when withdrawal symptoms will begin to arise.

What Factors Affect How Long Benadryl Stays in Your System?

Many factors that play a role in how long Benadryl stays in your body, including:

• Age – People older than 65 and younger than 12 might metabolize Benadryl slowly, which means it can stay in their system longer.

• Dosage – If you take high doses of Benadryl, it will take your body longer to eliminate it.

• Frequency of Use – The dosage of Benadryl is every 4 to 6 hours. If you are taking it more frequently, it might take your body longer to eliminate it.

• Metabolism – Some people have a naturally fast metabolism, while others have a slow one. The rate of your metabolism plays a role in how long Benadryl stays in your system.

• Interactions – Drinking alcohol or taking other medications at the same time as Benadryl can affect how long it stays in your system.

If you have health conditions like liver or kidney disease, you might not metabolize substances as quickly as everyone else.

If you are trying to pass a drug test, the best thing to do is stay abstinent from Benadryl use.

Can Drug Tests Detect Benadryl?

Benadryl leaves behind metabolites in your urine, blood, saliva, and hair. This is how drug tests can determine if you have recently used the drug. While Benadryl is not commonly tested for, healthcare professionals can use specialized tests to determine if you have consumed diphenhydramine.

Urine tests are the most commonly used drug tests. They can detect Benadryl in urine for 2 to 4 days after your last dose. Benadryl may cause a false positive for opioids in urine tests.

Blood tests offer a shorter window of detection. They can find Benadryl in your blood for 24 hours to 49 hours after your last dose.

Saliva tests look for Benadryl in your saliva. They can find traces of Benadryl for 2 to 4 days after you last consumed it.

Lastly, hair tests offer the longest window of detection. They can find any substance in your system for up to 90 days after you last abused it, including Benadryl.

Find Help for Benadryl Abuse and Addiction

If you or a loved one suffers from Benadryl abuse, you should seek professional help. Benadryl addiction can lead to several physical and mental health issues, including a high risk of overdosing. Thankfully, drug rehab programs can help you achieve long-term sobriety.

Contact New Jersey Addiction Interventions to learn more about how we can connect you to an addiction treatment center.

References:

1. The National Library of Medicine (NLM): Diphenhydramine Toxicity
2. Medline Plus: Diphenhydramine
3. Journal of Analytical Toxicology: Immunoassay Screening of Diphenhydramine (Benadryl®) in Urine and Blood Using a Newly Developed Assay
4. Journal of Allergy and Clinical Immunology: Levels for Pyribenzamine and Benadryl in blood and urine following a single orally administered dose