Diphenhydramine is well-known as its trade name – Benadryl. Diphenhydramine has been a common antihistamine used for the treatment of allergies, insomnia, and even the common cold for years. But how safe is diphenhydramine? Is it a dangerous drug that is hiding in plain sight?
As an over-the-counter antihistamine, diphenhydramine is incredibly easy to obtain. Diphenhydramine is available to anyone and everyone, and this is precisely what makes the drug dangerous.
The History of Diphenhydramine
George Rieveschl developed diphenhydramine in 1943 while working in the Department of Chemical Engineering at the University of Cincinnati. His focus was on relieving muscle spasms, but he worked on multiple projects. In 1946, diphenhydramine was approved by the United States Food and Drug Administration (FDA) as the first prescription antihistamine.
In the 1960s, diphenhydramine inspired the search for antidepressants that mimicked the effects that the drug had on serotonin. This resulted in the invention of SSRIs – selective serotonin reuptake inhibitors – which are antidepressants that increase the level of serotonin in the bran, like Prozac (fluoxetine) and zimelidine.
Medical Uses of Diphenhydramine
There are many medical uses of diphenhydramine. The drug is generally used to treat allergies, movement disorders, sleep issues, and nausea.
As of 2007, diphenhydramine was the most used antihistamine in the emergency room for acute allergic reactions. Injections of the drug are used to treat anaphylaxis in addition to epinephrine. You can purchase diphenhydramine in many topical forms as well, like creams, lotions, gels, and sprays. Topical forms of diphenhydramine are used to relieve itching caused by allergic reactions and do not have as many side effects as the oral or injected form of the drug.
Diphenhydramine can be used to treat movement disorders like Parkinson’s diseases and EPS – extrapyramidal symptoms – that are side effects of some antipsychotics.
The drug is commonly used as a nonprescription sleep aid, as well. Diphenhydramine is added to acetaminophen and ibuprofen and more to form the “PM” versions of the pain medicines. It has strong sedative properties that can cause psychological dependence. Additionally, diphenhydramine is an anxiolytic, which means it is an anxiety inhibitor.
Diphenhydramine can also be used to treat nausea when it occurs because of vertigo and motion sickness.
How Does Diphenhydramine Work?
Essentially, diphenhydramine works by attaching itself to histamine receptors and acting as an inverse agonist, which is just a fancy term that means it negates the action of the histamine. Histamine is the compound in the human body that produces the inflammation and itching in an allergic reaction.
In addition to blocking the effects of histamine, diphenhydramine is also a strong antimuscarinic which allows it to be used as an antiparkinson agent for movement disorders.
There are many dangers associated with the drug diphenhydramine. Not only is it not safe for certain age groups to use, but it is also very risky to use long term.
The Risk of Diphenhydramine for Senior Citizens
Diphenhydramine is an anticholinergic. This makes it affect the parasympathetic nervous system. As a person ages, their natural cholinergic agents decline, so taking medicine that further negates cholinergic agents in the body is not recommended.
For an older person, the use of diphenhydramine can affect cognitive function and cause delirium.
The Diphenhydramine Dementia Risk
Another risk of using diphenhydramine as an older adult is the heightened chance of forming dementia. A years-long study conducted by the University of Washington and Group Health, which is a Seattle healthcare system, called Adult Changes in Thought (ACT) tracked about 3,500 men and women aged 65 and older and all of the medicine each of them took
Led by Shelley Grey, a pharmacist at the University of Washington, the study determined the medicine taken by the participants for the decade prior to the study and the 7 years following its beginning. 800 of the participants in the study developed dementia. Once the study reached the anticholinergic drugs that the participants used, it found a link between those particular drugs and the development of dementia.
In fact, the study determined that “taking an anticholinergic for the equivalent of three years or more was associated with a 54% higher dementia risk than taking the same dose for three months or less.”
This study was the first to include nonprescription drugs. It serves as a reminder to always check all the medications that you are taking, and not just the prescription drugs.
The Risk of Diphenhydramine for Infants
Pediatricians do not recommend giving diphenhydramine to infants. The FDA warns that products that contain decongestants and antihistamines can cause potentially fatal side effects in children that are under 2 years of age – like convulsions and a rapid heart rate.
Other side effects that infants are more likely to experience after ingesting diphenhydramine can include dizziness, stomach cramps, nausea, diarrhea, and headaches. Since young children cannot communicate what they feel, it is often hard to tell when they are even experiencing adverse effects of the medicine.
That said, topical forms of diphenhydramine are generally safe to use on infants to relieve skin irritations and itching.
The Risk of Diphenhydramine as a Sleep-Aid
Diphenhydramine is often used as a sleep-aid, whether it’s in the form of Benadryl or an ingredient in a medicine marketing for aiding sleep. Histamines in the body can promote wakefulness, and, since diphenhydramine is an antihistamine, it blocks the wake-promoting histamines and causes drowsiness.
In 2017, the American Academy of Sleep Medicine, or AASM, “officially recommended against treating chronic insomnia with common over-the-counter antihistamine and analgesic sleep aids as well as herbal and nutritional substances, such as valerian and melatonin, because there is not enough evidence that they are effective and safe.”
According to Dr. Suzanne Bertisch, an assistant professor of medicine at Harvard Medical School, about 15-20% of adults in America take nonprescription sleep-aids each month. The risks of using these medicines that contain diphenhydramine as a sleep-aid are increased daytime sleepiness and grogginess, falls, and an increased risk of developing dementia and Alzheimer’s disease.
The Risk of Diphenhydramine and Pre-Existing Conditions
There are certain conditions and diseases that make it unsafe for a person to take diphenhydramine. Those conditions and diseases are:
- Digestive tract blockage
- Bladder obstruction
- Colostomy or ileostomy
- Liver or kidney disease
- Asthma, COPD, or other breathing disorder
- Chronic cough with mucus
- Heart disease
- Low blood pressure
- Thyroid disorder
- Taking potassium
Additionally, it is not known if diphenhydramine has any effect on fetuses, so doctors warn against taking it while pregnant. If you are breast-feeding, you can pass the drug onto your infant through breastmilk.
Overdosing on Diphenhydramine
Diphenhydramine has serious and fatal effects if you take too much of it. Overdosing on the drug can lead to cardiovascular collapse and death in as little as 2 hours!
Other overdose symptoms can include euphoria, dysphoria, hallucinations, tremors, seizures, disorientation, delirium, abnormal speech, acute megacolon, motor disturbances, abdominal pain, anxiety, severe dizziness and drowsiness, coma, and death.
Recreational Use of Diphenhydramine
Since diphenhydramine is so easily obtainable, even for minors, it is a common drug used by teenagers in order to get high. It is especially dangerous because most young people do not know the inherent risk of diphenhydramine overdose and how incredibly harmful it can be.
Diphenhydramine is said to have cocaine-like effects when taken in order to get high, most likely because of the anticholinergic effects of the drug.
Effects of a Diphenhydramine High
During a diphenhydramine high, the user will experience the following symptoms:
- Inability to urinate or defecate
- Enlarged pupils
- Rapid heartbeat
- Shaky hands and legs
After taking the drug, the user will start to feel the high within an hour, and it usually lasts about 6 to 8 hours with after-effects that can persist for more than 24 hours. When an excessive amount of diphenhydramine is taken, the half-life is extended, causing the drug’s effects to persist much longer than usual.
Addiction to Diphenhydramine
If you use the drug in large amounts often enough, you can become addicted to it. You’ll develop a very high tolerance for the drug and a mental addiction is unavoidable once that tolerance is developed. However, even with a tolerance, the risk of overdose is still very real.
Hiding Diphenhydramine Abuse
Hiding the abuse of diphenhydramine is difficult because of the drowsiness that it causes. Because the drug encourages the onset of things like sleepiness, short-term memory loss, and hallucinations, abuse of diphenhydramine is easily noticed.
However, while the high may be noticed easily, it is not easy to tell that it is caused by diphenhydramine because other, more well-known drugs can produce the same visible effects.
Diphenhydramine withdrawal is intense. You should never stop taking it cold turkey once you have developed a dependence on the drug. Like benzodiazepines and prescription opioids, the user must be slowly weaned off of the drug by consistently reducing the dose he or she takes each day. There are even “Benadryl detox programs” to help people ween off of excessive diphenhydramine use.
Diphenhydramine withdrawal symptoms include:
- Constant restlessness
- Difficulty sleeping
- Cold or hot sweats
- Cold symptoms
Diphenhydramine continues to be sold over the counter with almost no restrictions, so users should stay away from pharmacies and areas that sell the drug because it could trigger a relapse. Like any other addiction, the user should continue to work on staying away from the drug and join counseling, group therapy, or online communities for support. We believe that an intensive stay at a facility like The Hills will allow people dependent on diphenhydramine to detox from their drug of choice and move towards healing in ways that promote long-lasting stability.
What to Take Other than Diphenhydramine
So, you honestly suffer from allergies, and you are forced to take a daily antihistamine. What are you supposed to do? There are first-generation and second-generation antihistamines available. For daily allergy management, second-generation antihistamines are typically your best bet.
Diphenhydramine is a first-generation antihistamine. First-generation antihistamines are the oldest on the market and are typically the cheapest. These antihistamines not only block H1 receptors, but they also block adrenergic receptors and 5-HT receptors – making the drug non-selective.
In addition, first-generation antihistamines are known for their potent anticholinergic effects that cause them to have more side effects and be more dangerous for certain age groups.
There are multiple classes of first-generation antihistamines – ethylenediamines, ethanolamines, alkylamines, piperazines, tricyclics, and tetracyclics. Diphenhydramine belongs to the ethanolamine class of antihistamines.
The benefits of second-generation antihistamines are their selectivity. They are made to only target the peripheral H1 receptors and to stay away from the H1 receptors that are connected to the central nervous system and the cholinergic receptors. The selectivity of second-generation antihistamines greatly reduces the chance of adverse reactions to the drugs.
Second-generation antihistamines include cetirizine (Zyrtec) and loratadine (Claritin). It is important to note that cetirizine is known to interact with some psychoactive drugs like benzodiazepines that affect the central nervous system. This serves as a reminder to always check drug interaction between all the medicines you are taking – both prescription and over-the-counter.
Third-generation is the informal term given to second-generation antihistamines that include derivatives of enantiomer or metabolite in their makeup. The inclusion of these derivatives is supposed to make the antihistamines work even better with fewer adverse reactions than second-generation antihistamines. However, there has not been enough research done to determine if third-generation antihistamines are better than their second-generation counterparts.
Third-generation antihistamines are levocetirizine, desloratadine, and fexofenadine (Allegra).
The Verdict Is
Generally, the safest antihistamines to take for all ages are second and third-generation antihistamines. Since all bodies are different, you may need to try a few different kinds to find the perfect one for you. However, you can rest assured that you won’t suffer from diphenhydramine dependence or side effects in the meantime.
Benadryl is a household name, but diphenhydramine is not. Many people know of the dangers of illicit drugs and certain prescription drugs, but over-the-counter medication is commonly seen as safe, so people don’t realize that they can also be dangerous.
Make it a point to look at all of your medications today. The internet can be a helpful tool, and it can allow you to look for drug interactions that you may need to know about. If diphenhydramine is in your daily medicine routine, consider talking to your doctor and changing it out for a less risky substitute.
It’s always better to be safe than sedated!
If you have become dependent on diphenhydramine and are looking for a way to break free from addiction, you have options. The Hills, a rehab facility in Southern California, is here to help. Contact us today to learn how our facility can help you on the path to sobriety!