What is Diphenhydramine Toxicity (Benadryl Toxicity)?
Diphenhydramine is a type of medication known as a first-generation antihistamine, which also has properties that can lessen the body’s natural response to certain substances and can induce sedation. This medication is most often used to treat conditions like nausea and vomiting, allergies, severe allergic reactions like anaphylaxis, and to help with sleep. Despite its many medical uses, diphenhydramine is also one of the most commonly misused medications in the U.S. Using too much of this medication can lead to serious, sometimes deadly, consequences if not treated quickly and properly.
What Causes Diphenhydramine Toxicity (Benadryl Toxicity)?
Poisoning from diphenhydramine, a common over-the-counter medicine, can happen if it is consumed, applied on the skin, or received through an intravenous drip. However, it’s more likely to result from swallowing the medicine because this form of diphenhydramine is easy to access compared to other forms.
Overdosing on diphenhydramine can be accidental or deliberate. While some people might intentionally consume large amounts for self-harm or suicide, others might do it to experience positive or euphoric feelings.
It’s significant to remember that diphenhydramine is often included in other over-the-counter combined medicines like cough and cold remedies.
Risk Factors and Frequency for Diphenhydramine Toxicity (Benadryl Toxicity)
In 2016, a study found that 3.2% of drug overdose deaths in the U.S were caused by diphenhydramine, a common medication. The study also found that diphenhydramine was one of the top 15 drugs connected with drug overdose deaths in America. The majority of these overdoses or cases of poisoning took place in children aged 6 years or younger.
Signs and Symptoms of Diphenhydramine Toxicity (Benadryl Toxicity)
Diphenhydramine toxicity refers to the harmful effects that can occur when a person takes too much of the medication diphenhydramine. These effects range from mild to severe and may affect many parts of the body, especially the central nervous system and bodily functions controlled by the nerve endings, known as anticholinergic symptoms.
Mild to moderate cases typically present anticholinergic symptoms like dry mouth and throat, confusion, rapid heart rate, dilated pupils, inability to urinate, increased body temperature, and reduced bowel sounds. For individuals with a severe scenario of toxicity, they can experience severe confusion or delirium, seizures, psychosis, low blood pressure, muscle spasms, hallucinations, and heart rhythm abnormalities. In rare instances, prolonged episodes of severe symptoms can lead to muscle breakdown and kidney failure.
Here is a list of possible symptoms:
- Dry mouth and throat
- Disorientation/confusion
- Rapid heart rate
- Dilated pupils
- Inability to urinate
- Increased body temperature
- Reduced bowel sounds
- Severe confusion or delirium (in severe cases)
- Seizures (in severe cases)
- Psychosis (in severe cases)
- Low blood pressure (in severe cases)
- Muscle spasms (in severe cases)
- Hallucinations (in severe cases)
- Heart rhythm abnormalities (in severe cases)
- Muscle breakdown and kidney failure (in rare cases)
Testing for Diphenhydramine Toxicity (Benadryl Toxicity)
If someone arrives in the emergency room because of intoxication or a suspected drug overdose, doctors will use the ABCDE approach to assess their condition swiftly. This method checks the Airway, Breathing, Circulation, Disability status, and Exposure to harmful substances. They will also measure vital signs – blood pressure, heartbeat, breathing rate, body temperature, and the amount of oxygen in the bloodstream. This helps them to understand the seriousness of the situation.
Doctors will do an EKG (a test to check the heart’s electrical activity) to see if there are any irregular heart rhythms, such as a condition called ‘torsades de pointes’. They will also check the level of acetaminophen, a common painkiller, in the blood. This is to confirm or rule out its presence alongside other substances.
One substance that might be involved is diphenhydramine. Doctors usually can’t gain much useful information from checking diphenhydramine levels in the blood, and such a test is often not readily available. Although the body processes diphenhydramine mainly through the liver, it’s not expected to cause liver problems or abnormal liver tests results.
To prevent complications, doctors will check a few more things. They’ll measure the level of creatinine in the bloodstream, how much urine is being produced, and the level of a substance called creatine phosphokinase. These checks help to rule out ‘rhabdomyolysis’, a condition where muscle tissue breakdown that may occur if the person has had a seizure.
Treatment Options for Diphenhydramine Toxicity (Benadryl Toxicity)
If someone swallows diphenhydramine, a common antihistamine, detoxification strategies could be beneficial within the first hour. One such technique is giving the patient activated charcoal, especially since the chemical effects of the drug might slow down digestion, leading to an extended absorption period. However, it’s crucial not to use this strategy in patients who aren’t fully conscious unless they have a protected airway. Other detoxification methods, such as inducing vomiting, using laxatives, or flushing the stomach, are generally not recommended due to their lack of proven effectiveness and potential complications.
Right now, there’s no specific antidote for reversing the effects of diphenhydramine toxicity. The main treatment strategy is to manage the specific symptoms of poisoning or overdose. Various drugs and techniques can be used, including benzodiazepines for seizures, sodium bicarbonate for heart rhythm issues, and a particular technique called VA-ECMO for supporting the body’s blood flow. While a compound called physostigmine has been used to restore acetylcholine (a crucial brain chemical), it’s currently not available. The use of intravenous lipid emulsion therapy, which involves injecting a fatty solution into the vein, has been suggested but remains a contentious topic. Hemodialysis, a blood-cleaning technique, isn’t commonly recommended because diphenhydramine isn’t effectively removed using this method.
In children, if they’ve ingested diphenhydramine in a dose less than 7.5 mg/kg, they could be safely observed at home. However, if any behavioral changes like more than mild drowsiness or stimulation occur, they should be taken to an emergency department immediately. If a child ingests more than 7.5 mg/kg of diphenhydramine, they should be immediately referred to a healthcare facility.
What else can Diphenhydramine Toxicity (Benadryl Toxicity) be?
In simpler terms, when deciding what might be causing symptoms like changes in mental state, fast heart rate, difficulty in urinating, fits, or other symptoms related to the nervous system, physicians must consider any substances or health conditions that might lead to these. They should also think about other serious health conditions like meningitis or systemic infections.
Determining when confusion or delirium started can aid in figuring out what’s causing it. For instance, delirium caused by toxin exposure typically happens quickly and without warning, more so than delirium caused by organic health conditions.
Furthermore, if a patient is experiencing changes in their mental state, is running a high temperature, and is restless, the doctor should also consider whether a salicylate overdose (an active ingredient in many medicines like aspirin) could be the cause.
What to expect with Diphenhydramine Toxicity (Benadryl Toxicity)
If a diphenhydramine overdose is quickly identified and managed, the outlook is generally positive. Most people are likely to recover; however, long hospital stays might lead to complications such as pneumonia. If a patient doesn’t show any symptoms after four hours of taking diphenhydramine by mouth, or eight hours after skin exposure, they might be ready to go home. But, if a patient shows moderate to severe signs of anticholinergic toxicity – a type of poisoning – they may need to stay in the hospital.
Possible Complications When Diagnosed with Diphenhydramine Toxicity (Benadryl Toxicity)
- Breathing failure
- Irregular heart rhythms
- Heart stopping
- Breakdown of muscle tissue
- Seizures
- Death
Preventing Diphenhydramine Toxicity (Benadryl Toxicity)
Teaching both patients and parents of young children about correct medication use is crucial. Parents need to know that they should not give diphenhydramine, a common medication found in many over-the-counter products, to children under the age of 12 years without a doctor’s guidance. It’s also important to educate patients about the presence of diphenhydramine and other similar drugs in many over-the-counter products.
