[ chemical formula: C17H21NO · HCl ; also known as benzhydramine hydrochloride
or dimethyle-thylamine hydrochloride ]
Use of Drug-
- Increases the effect of other pain medications
- Relieves or prevents the symptoms of hay fever and
other types of allergies
[ Marketed under brand name Benadryl; Alleran
- Night-time sedation
[ Marketed under brand names Sominex® (SmithKline
Beecham); Simply Sleep (McNeil Consumer
Healthcare, McNeil-PPC, Inc.); et al. ]
- Relieve cough due to cold and hay fever
- Motion sickness
- Decrease stiffness and tremors in patients with Parkinson’s
"nighttime sleep aid"- helps to reduce
difficulty falling asleep.
As well as being a sedative, diphenhydramine hydrochloride also has anticholinergic and antiemetic qualities. Anticholinergic means that it blocks the neurotransmitter acetylcholine and its antiemetic properties means that it alleviates nausea and vomiting, which is why it is also sometimes used to treat motion sickness.
Recommended dosage: 25 mg.
Diphenhydramine hydrochloride is effective within 15 to 30 minutes of being taken orally. Its effects will last approximately 4 to 8 hours. Almost all of the diphenhydramine hydrochloride, about 95%, is metabolised by the liver.
Claimed to be "non habit-forming". Potentially carcinogenic (see Links
Typical Inactive Ingredients: Dibasic Calcium
Phosphate, coloring (FD&C Blue #1 Aluminum Lake), Magnesium Sterate,
Dihydrate, Hydroxypropyl Methylcellulose, Magnesium Stearate, Polyethylene
Glycol, et al.
How This Drug Works:
Diphenhydramine HCL belongs to a group of medicines called antihistamines.
They work by preventing effects of substance called histamine which
is produced by the body.
When Does it Start to Work: 15-30 minutes
How Long Will it Work: 4-6 hours
Guidelines for Use: Take this medication only
as directed. Do NOT take more of it or more often than recommended.
To do so may increase the chance of side effects. If you take this medication
regularly and you miss a dose, take as soon as possible. However, if
it is almost time for your next dose, skip the missed dose and go back
to your regular dosing schedule. Do NOT double your doses. This medication
can be taken with food or a glass of water or milk to lessen stomach
irritation. Antihistamines will add to the effects of alcohol and medicines
that slow down the nervous system, so avoid their use. If you are taking
this medication for motion sickness, take it at least 30 minutes or,
even better, 1-2 hours before you begin to travel. This medicine may
cause dryness of the mouth, nose, and throat. For temporary relief you
may use sugarless candy or gum or melt bits of ice in your mouth. Make
sure your physician is aware you are taking this medicine if you have
symptoms of appendicitis such as stomach or lower abdominal pain, cramping,
or soreness. Make sure you know how you react to this medicine before
you drive, use machines, or do anything else that could be dangerous
if you are not alert. Make sure your physician is aware you are taking
this medicine if you are pregnant or nursing. The possibility of fetal
harm does exist, so notify your physician before taking the medication.
Do NOT take this medicine in addition to any other sedative, tranquilizer,
of pain medication without checking with your physician.
Possible Side Effects: Drowsiness Thickening
of mucous Confusion Changes in vision Dizziness Difficult or painful
urination Increased sensitivity of skin to the sun Fast heartbeat Loss
of appetite Nightmares Unusual excitement, nervousness, restlessness
or irritability Increased sweating Ringing or buzzing in ears
Symptoms of Overdose: Trouble in sleeping; Hallucinations;
Shortness of breath, or troubled breathing; Feeling faint; Severe dryness
of the mouth, nose, or throat; Clumsiness or unsteadiness; Severe drowsiness;
Flushing or redness of face; Convulsions (seizures)
An antihistamine closely related to Diphenhydramine is Doxylamine Succinate. Doxylamine succinate [C 21 H 28 N 2 O 5] is sold under the brand name "Unisom" as a "nighttime sleep-aid".