Updated on November 8, 2023
6 min read

How Dangerous is the Combination of Benadryl and Alcohol?

What is Benadryl?

Benadryl is a common over-the-counter (OTC) medication commonly used to treat allergies. The active ingredient in all Benadryl formulations is diphenhydramine. This is an antihistamine that blocks allergy symptoms.1

The medication is available in the following forms, depending on the intended use:

  • Liquid
  • Pill (most common)
  • Gel
  • Cream
  • Spray

What Happens if You Mix Benadryl and Alcohol?

Both Benadryl and alcohol affect the nervous system. They are both central nervous system (CNS) depressants. Introducing them into your system together negatively affects the functionality of the central nervous system. This affects essential processes like breathing. 

The effects of mixing alcohol and Benadryl vary from one person to another. However, it's best to refrain from drinking alcohol while taking Benadryl. 


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6 Dangers of Mixing Benadryl and Alcohol

Since you can get Benadryl without a prescription at pharmacies and grocery stores, you may assume it's safe to use. However, Benadryl is a powerful medication with dangers.

Here's what you need to know about the severe side effects of mixing Benadryl and alcohol:

1. Cognitive impairments

Diphenhydramine is the active ingredient in Benadryl. This ingredient prevents the function of an endogenous (produced inside the body) neurotransmitter called acetylcholine.

Acetylcholine is critical for learning, memory, and movement, and blocking its action temporarily impairs these processes. 

Alcohol also has a temporary negative effect on learning and memory. When coupled, alcohol and Benadryl may significantly impair these cognitive capabilities.

2. Loss of consciousness

Some people are more likely than others to pass out while sedated.

Combining Benadryl with alcohol is also more likely to induce a state of unconsciousness in these people. This can be dangerous due to the risk of falls and other related injuries.

Mixing Benadryl and alcohol also increases the risk of overdose, which may be life-threatening.

3. Complications in seniors

The body's capacity to break down alcohol decreases as it ages. As a result, alcohol may stay in the system of older people for longer than it does in younger people. 

For seniors, a dangerous mix of Benadryl and alcohol may cause a harmful interaction in the body.

Sedation and disorientation may cause problems with their motor abilities. This increases the risk of falls and other accidents.

4. Dehydration

Benadryl dries up the nasal passages, which helps reduce congestion. While this may help those suffering from allergies, taken together with alcohol, dehydration can occur.

Similarly, alcohol is a known diuretic.

Alcohol causes the body to lose water through the renal system, including the:

  • Kidneys
  • Bladder
  • Ureter

A combination of alcohol and Benadryl in the body can cause:

  • Drowsiness
  • Gastrointestinal discomfort
  • Severe hangovers

5. Increased Risk of Dementia

A University of Washington study found that using antihistamines regularly for a long time raises your chance of dementia.4 The risk of dementia was 54% higher among people who took Benadryl for three years than those who took it for three months or less.5 

Excessive alcohol use is a problem in the same way.8 Combining these drugs is much more dangerous because of this additional risk.

6. Risk of injury/accident

Even without combining Benadryl with alcohol, you shouldn't drive or operate machinery. Benadryl can depress the central nervous system, affecting a person's ability to stay alert. 

The effect of Benadryl on the ability of a driver to stay alert is greater than that of alcohol.6 Mixing the two can be dangerous not only to you but also to those around you.

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Can I Overdose on Benadryl and Alcohol?

Drinking alcohol while taking Benadryl can lead to an overdose. Considering its availability as an OTC medication, the risk of someone mixing it with alcohol is much higher.

There's also an increased risk of Benadryl-alcohol overdose. Benadryl is known to stay in the body system for a long time.

Symptoms of Benadryl and alcohol overdose include: 

  • Blurry vision
  • Rapid heart rate
  • Extreme drowsiness
  • Nausea or vomiting
  • Loss of balance or inability to walk
  • Dry, red skin
  • Low blood pressure
  • Ringing in the ears (tinnitus)

There must be enough of both drugs in the system for an overdose to occur. The amount may vary from person to person.

Health experts recommend completely refraining from alcohol when using Benadryl.

Uses of Benadryl

Oral Benadryl is used to relieve allergy symptoms such as:2

  • Watery eyes
  • Itchy eyes
  • Sneezing
  • Coughing
  • Runny nose
  • Stuffy nose or throat
  • Nausea
  • Vomiting

As an anti-nausea drug, Benadryl is often used to keep motion sickness at bay. It's also used as a sleep aid and reduces irritation caused by bug bites and rashes.

Additionally, Benadryl may help reduce abnormal movements that occur with early-stage Parkinson's disease.

Note: Benadryl treats symptoms temporarily, but doesn't address the root cause of ailments or speed up the recovery process. This drug isn't recommended for managing sleeplessness in children.

Side Effects & Risks of Taking Benadryl

Benadryl can cause both mild and severe side effects, depending on the person.

Short-term side effects:

  • Dizziness
  • weakness
  • Dry mouth, nose, or throat
  • Headache

Adverse side effects:

  • Dementia
  • Difficulty breathing
  • Seizures
  • Disturbed coordination
  • Increased heartbeat
  • Euphoria
  • Early menses

Long-term side effects:

  • Memory loss
  • Blurred vision
  • Dependence
  • Anxiety

Severe side effects:

  • Hallucination
  • Seizures
  • Flushed skin
  • Elevated body temperature
  • Urinary retention and acute kidney injury
  • Heart rhythm disturbances
  • Rhabdomyolysis

How Long After Taking Antihistamines Can I Drink Alcohol?

Antihistamines such as Benadryl are known to stay in the body for up to 48 hours. But this could be extended in older adults. It's highly recommended that you wait until the drugs wear off before drinking alcohol. 

The rate of elimination from the system varies from person to person. As such, it's essential to consult your healthcare provider about when it's safe to resume alcohol use after antihistamine medication.

Do I Have a Drinking Problem?

You may have a drinking problem if your alcohol intake habits cause distress or harm in your life and that of your family and loved ones. The extent of the problem varies from one person to another. 

If you're starting to lose control over your drinking habits or can't cope without a drink, then you have an alcohol problem.

Signs that you may have a drinking problem include:9

  • Being unable to reduce the amount of alcohol you drink
  • Aiming to cut down on how much you drink or making unsuccessful attempts to do so
  • Spending a lot of time drinking, finding alcohol, or recovering from alcohol use
  • Experiencing an intense craving or urge to drink
  • Failing to fulfill essential obligations at work, school, or home due to repeated alcohol use
  • Continuing to drink even though you know it's causing physical, social, or interpersonal problems
  • Stopping or reducing social and work activities and hobbies
  • Using alcohol in situations where it's unsafe, like when driving or swimming
  • Developing a tolerance to alcohol, so you require more to feel its effect, or you have a reduced impact from the same amount
  • Experiencing withdrawal symptoms when you don't drink or drinking to avoid these symptoms

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Mixing NyQuil and alcohol is dangerous and can have serious consequences. It increases the chance of an overdose, liver damage, impaired immune system, and addiction.

Moreover, you shouldn't use NyQuil as a sleep aid or for long-term treatment of symptoms. If you take more than the recommended dose, you may experience withdrawal symptoms.

Talking to your doctor before taking NyQuil and other medications is best. They can help you understand the possible risks and decide if it's a safe choice for you.

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Updated on November 8, 2023
9 sources cited
Updated on November 8, 2023
  1. Diphenhydramine” MedlinePlus, August 2018
  2. Allergy Symptoms,” American College of Allergy, Asthma & Immunology
  3. Diphenhydramine chewable tablet,” Cleveland Clinic
  4. Common anticholinergic drugs like Benadryl linked to increased dementia risk,” Harvard Health, 24 June, 2019
  5. Gray SL, Anderson ML, Dublin S, et al. Cumulative Use of Strong Anticholinergics and Incident Dementia: A Prospective Cohort Study. JAMA Intern Med. 2015;175:401–407
  6. Drugs and Human Performance Fact Sheets,” National Highway Traffic Safety Administration (NHTSA) Washington State Patrol, April 2004
  7. Treatment for Alcohol Problems: Finding and Getting Help,” National Institute of Health (NIH), 2014
  8. Rehm, Jürgen et al. “Alcohol use and dementia: a systematic scoping review.” Alzheimer's research & therapy vol. 11,1 1. 5 Jan. 2019
  9. Alcohol use disorder, Mayo Clinic, July 2018

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