If you’ve had an itchy rash, cough, or runny nose, you’ve probably taken Benadryl before. Benadryl (diphenhydramine) is an over-the-counter antihistamine that can treat allergic reactions, hay fever, and the common cold.[1] Because it can cause drowsiness, some people might use it to manage insomnia.
Even though Benadryl is considered safe to use, some people abuse it. Because of the drowsiness it can cause, individuals might take high doses of it to experience mind-altering effects. When taken in large amounts, sometimes diphenhydramine can lead to a detachment from reality and hallucinations.
While most drug tests do not automatically screen for Benadryl, if a facilitator knows you have a history of abusing the drug, they might test for it. Benadryl can stay in your system for up to 45 hours.[2]
It’s also important to note that diphenhydramine can cause false-positive results for opioids. If you are trying to pass a drug screen for opioids, let the facilitator know that you’ve recently used Benadryl.
Even though Benadryl leaves your system within 45 hours, metabolites are left behind that allow drug tests to find it for a longer period. For example, urine tests can find Benadryl in your system for 2 to 4 days after your last dose.
In this article, you will learn:
- What is diphenhydramine (Benadryl)?
- How long does diphenhydramine stay in your system?
- Can drug tests detect diphenhydramine?
What is Benadryl?
Benadryl is an over-the-counter medication that can treat allergy symptoms, cold symptoms, and can be used as a sleep aid. It works to relieve itchiness, rashes, and cold symptoms by blocking histamine in your brain. That said, Benadryl can lead to side effects like drowsiness, which can be attractive to people struggling with substance abuse issues.
The side effects of Benadryl may include:[1]
- Dry mouth, nose, and throat
- Dizziness and drowsiness
- Nausea and vomiting
- Loss of appetite
- Constipation
- Chest congestion
- Headaches
- Muscle weakness and aches
- Excitement or nervousness (especially among children)
If you take a large dose of diphenhydramine, you might experience a drowsy high, changes in sensory perception, and slight hallucinations. However, taking too much Benadryl can lead to life-threatening overdoses. In other words, you should seek professional help if you are stuck in a cycle of diphenhydramine abuse.
What is the Half-Life of Benadryl?
Benadryl will begin to affect you within 30 minutes of consuming it. The effects can last anywhere from 4 to 6 hours.
Understanding how long diphenhydramine remains in your system requires you to know what a half-life is. A drug’s half-life explains how long it takes your body to eliminate half of the dose. It can take 4 to 5 half-lives for your system to completely flush out a drug.
The half-life of Benadryl is about 9 hours.[2] This means it can stay in your system for up to 45 hours. If you stopped taking Benadryl after a period of dependence, you will begin to experience withdrawal in 24 to 48 hours.
Can Drug Tests Detect Benadryl?
Even though diphenhydramine leaves your system within 45 hours, it leaves behind metabolites in certain areas of your body. This is how drug tests can detect whether you’ve used Benadryl recently. The exact length of time that a drug screening tool can find Benadryl in your system depends on what type of test is being used.
Urine
Urine tests are the most commonly used drug screening tool, as they are minimally invasive and relatively cheap to use. You might take a urine test at a doctor’s office, a rehab center, a probation office, during pre-employment drug screening, or in a variety of other settings.
These tests can detect Benadryl in urine for 2 to 4 days after you last used it. However, people do not generally test for diphenhydramine unless they have a reason to think that you have abused the allergy medication.
Blood
Blood tests are not as common as urine screenings because they are invasive, requiring a blood draw to be analyzed. Additionally, their window of detection tends to be shorter than urine tests. However, hospitals might use them in emergencies when you are unable to provide a urine sample.
Blood tests can find Benadryl in your system for 24 to 48 hours after you last used it.
Saliva
Similar to blood tests, saliva tests offer a short window of detection. Because of this, they are not used frequently. However, law enforcement officers might use them during field sobriety tests to determine if you were operating a vehicle under the influence of drugs.
If you are taking a saliva test for Benadryl, you can test positive for 2 to 4 days after you last used it.
Hair
Hair tests offer the longest window of detection out of any type of drug screening tool. That said, medical professionals rarely use them because they can offer unreliable results due to discrimination based on things like hair color. Despite this, some high-security clearance jobs use them to test before offering employment.
Hair follicle drug testing can find any substance in your system (including Benadryl) for up to 90 days after you last used it.
Get Connected to a Benadryl Rehab Program
If you or a loved one regularly abuses diphenhydramine, you might be suffering from a substance use disorder. The long-term effects of diphenhydramine can be intense, making it important that you seek professional help to achieve sobriety. At Archstone Behavioral Health, we offer personalized and evidence-based care to ensure our clients have access to the tools and support they need to be successful in recovery.
Contact us today for more information on how we can help you recover from Benadryl abuse and addiction.
References:
- Medline Plus: Diphenhydramine
- The National Library of Medicine (NLM): Diphenhydramine Toxicity
- American Society for Clinical Pharmacology & Therapeutics: Metabolic disposition of diphenhydramine
