Diphenhydramine Hydrochloride

💊 What is Diphenhydramine Hydrochloride used for?

• •Allergic reactions to blood or plasma
• •Anaphylaxis (a severe allergic reaction), used alongside epinephrine and other standard measures after the acute symptoms are under control
• •Other uncomplicated allergic conditions of the immediate type, when oral therapy is impossible or not advised
• •Active treatment of motion sickness
• •Parkinsonism, when oral therapy is impossible or not advised, including in older adults who cannot tolerate stronger medicines, mild cases in other age groups, and some other cases in combination with other medicines

How it works

The label describes diphenhydramine as an antihistamine. It also says the drug has an atropine-like action, which means it can have drying effects on the body.

How it is usually taken

• •This product is for intravenous (into a vein) or deep intramuscular (deep into a muscle) use only. The label says it is used when the oral (by mouth) form is impractical. The label says the dose should be individualized to each patient's needs and response. Before use, the label says the product should be checked visually for particles and discoloration, when the solution and container allow. The label also says the infusion rate generally should not exceed 25 mg per minute. Follow the instructions from your prescriber or pharmacist.

Comes as

• •Injection solution, 50 mg per mL, in single-dose vials (25 vials per carton)

⚠️ Diphenhydramine Hydrochloride side effects

🛑 Who should not take Diphenhydramine Hydrochloride, and who should be careful

The label says not to take it if

• 🚨The label says it should not be used in newborns (neonates) or premature infants.
• 🚨The label says antihistamine therapy is contraindicated in nursing mothers.
• 🚨The label says it should not be used as a local anesthetic because of the risk of local tissue death (necrosis).
• 🚨The label says it is contraindicated in people with hypersensitivity (allergy) to diphenhydramine hydrochloride or to other antihistamines of similar chemical structure.

Tell your doctor before taking it if

• •Tell your prescriber about any history of narrow-angle glaucoma, stenosing peptic ulcer, pyloroduodenal obstruction, symptomatic prostatic hypertrophy, or bladder-neck obstruction. The label says antihistamines should be used with considerable caution in these conditions.
• •The label says caution is needed in people with bronchial asthma, lower respiratory disease, increased intraocular pressure, hyperthyroidism, cardiovascular disease, or hypertension.
• •The label says older adults (about 60 or older) are more likely to have dizziness, sedation, and low blood pressure.
• •The label says children may have more mental and excitation effects, and that overdose in children can be dangerous.

🔀 Diphenhydramine Hydrochloride with other medicines, food and alcohol

The label says to discuss these with your doctor or pharmacist

• •Alcohol: the label says diphenhydramine has an additive effect with alcohol.
• •Other CNS depressants (such as hypnotics, sedatives, and tranquilizers): the label says these have additive effects with diphenhydramine.
• •MAO inhibitors: the label says these prolong and intensify the drying (anticholinergic) effects of antihistamines.

Alcohol and food

The label says diphenhydramine has an additive effect with alcohol, meaning the two together can increase drowsiness. The label does not give any food instructions.

🤰 Diphenhydramine Hydrochloride in pregnancy and breastfeeding

Pregnancy

The label says animal studies at doses up to 5 times the human dose showed no evidence of impaired fertility or harm to the fetus. It also says there are no adequate and well-controlled studies in pregnant women, so the label says it should be used during pregnancy only if clearly needed.

Breastfeeding

The label says antihistamine therapy is contraindicated in nursing mothers because of the higher risk of antihistamines for infants.

🗓️ Storage, missed doses and taking too much

Storage

The label says to store at 20° to 25°C (68° to 77°F), with excursions permitted between 15° and 30°C (59° and 86°F). Protect from light and keep covered in the carton until time of use. Discard any unused portion.

If a dose is missed

The label does not say.

If too much is taken

The label says antihistamine overdose may cause effects that range from central nervous system depression to stimulation, with stimulation more likely in children. Atropine-like signs may include dry mouth, fixed and dilated pupils, flushing, and stomach or bowel symptoms. The label says stimulants should not be used, and vasopressors may be used to treat low blood pressure.

🗒️ Questions to ask about Diphenhydramine Hydrochloride

• Is an injection the right form of diphenhydramine for my condition, given that the label says it is used when a by-mouth form is impractical?
• Do I have any of the conditions the label mentions, such as glaucoma, asthma, prostate problems, or heart disease?
• Am I taking any medicines that could add to drowsiness, such as sedatives, tranquilizers, or MAO inhibitors?
• How will I know if I am having a severe allergic reaction, and what should I do?
• Could this medicine affect my ability to drive or operate machinery?
• If I am pregnant or breastfeeding, what are my options, given the label's warnings?

❓ Diphenhydramine Hydrochloride: frequently asked questions