Diphenhydramine is a medication used to alleviate allergy symptoms, treat insomnia, and reduce the incidence of motion sickness. It is an antihistamine medication, which blocks the action of the naturally-occurring compound histamine that is involved in allergic reactions. Antihistamines are not normally known for their addictive potential, but diphenhydramine addiction is a medical condition that does occur occasionally. Certain signs can reveal an addiction or psychological dependence to this drug.
Physical dependence to this medication usually does not develop, although long-term, daily use for sleep can sometimes lead to a psychological dependence on the drug for this purpose. This may be considered a form of diphenhydramine addiction, since the individual will be unable to sleep without taking this drug. In addition to insomnia, another sign of this dependence is the formation of tolerance, or requiring progressively more diphenhydramine to get to sleep.
Another form of psychological dependence and tolerance may occur when taking this medication for long periods of time for allergy relief. When an individual accustomed to taking this medication stops taking it suddenly, he or she may experience allergy-like symptoms, even when he or she is not actually exposed to the allergen. This type of response is psychological in nature, however, and does not denote an actual physical addiction.
Research has revealed some rare cases of extreme diphenhydramine addiction. One study focused on a woman that exhibited several signs of addiction who had taken quantities of this drug that would cause extreme adverse effects in most people, without any apparent ill effect. When denied access to the drug, she was unable to sleep at all. For this reason, she had to be tapered off his medication slowly so she could get to sleep each night. Other signs of diphenhydramine addiction that she displayed included tremors and unpleasant side effects from her antipsychotic medication when she was deprived of the antihistamine drug.
Some signs of diphenhydramine addiction relate to the experience of using the medication. People who are likely to misuse this drug report a calming or euphoric effect when taking the drug. They may also demonstrate intoxicated behavior from taking more of this medication than directed. At doses that slightly exceed the recommended dose, individuals may behave as if they are drunk, but at higher doses they may act unpredictably and respond to hallucinations. Extremely high doses may even result in delirious behavior that can require hospitalization.