The organ that Benadryl is bad for is the bladder and the kidneys as well as your heart and brain.
However when Benadryl is taken at the normal recommended dosages, it's not directly toxic to any single organ in your body.
But Benadryl's anticholinergic properties which block a key nervous system chemical can negatively impact your bladder and kidneys as well as your heart and brain.
Benadryl crosses your blood-brain barrier and frequently causes sedation, confusion, dizziness and even next day cognitive impairment.
And long term use of Benadryl in older adults is also linked to a higher risk of developing cognitive decline.
High doses or toxic doses of Benadryl can also cause dangerous and even life threatening irregular heart rhythms also known as arrhythmias and even cardiac arrest.
And Benadryl can also cause urinary retention, which makes it hard for you to empty your bladder completely.
And this buildup of urine in the bladder places extra pressure on your kidneys, which can also result in acute kidney injury, especially in older adults.
If you or someone else took too much Benadryl or are experiencing any severe confusion, chest pain or an inability to urinate you should seek emergency medical care.
People who should avoid Benadryl are people who have a history of allergic reactions to diphenhydramine, narrow-angle glaucoma, or certain breathing and prostate issues should avoid taking Benadryl.
High-Risk Health Conditions of taking Benadryl include:
Narrow-angle glaucoma: Benadryl can increase eye pressure and worsen symptoms.
Breathing problems: Conditions like asthma, bronchitis, or COPD can worsen because the drug thickens mucus in the throat.
Bladder or prostate issues: An enlarged prostate or trouble urinating can become severe.
Dementia or memory problems: Regular use can increase confusion or risk of cognitive decline.
Seizure disorders: Epilepsy or conditions causing seizures can be negatively impacted.
Age and Special Groups who should avoid Benadryl include:
Older adults (65+): Seniors face a higher risk of heavy drowsiness, confusion, falls, and side effects.
Young children: Young children and infants require extreme caution or medical direction due to high dosing risks.
Breastfeeding: The drug Benadryl passes into breast milk and can make a nursing infant overly drowsy.
Drug and Substance Interactions with Benadryl include:
Alcohol: Combining alcohol with Benadryl increases extreme sleepiness and dangerous side effects.
Other sedatives or antihistamines: Doubling up on antihistamines or sleep aids raises the risk of overdose.