Diphenhydramine Hcl 50mg Caps

Diphenhydramine is a first-generation antihistamine that competitively blocks histamine H1 receptors in the periphery and in the central nervous system (CNS). This antagonism prevents histamine from binding to its receptors, thereby reducing the effects of histamine, such as vasodilation, increased capillary permeability, and pruritus. Its high lipophilicity allows it to readily cross the blood-brain barrier, leading to significant CNS effects including sedation. It also possesses significant anticholinergic (muscarinic receptor blockade) effects, which contribute to its drying effects (e.g., reduced nasal secretions, dry mouth) and antiemetic properties.

Urgent Side Effects: Seek Medical Help Right Away

While rare, some people may experience severe and potentially life-threatening side effects when taking this medication. If you notice any of the following symptoms, contact your doctor or seek immediate medical attention:

Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Severe dizziness or fainting
Changes in balance
Feeling less alert than usual

Other Possible Side Effects

Like all medications, this drug can cause side effects. Although many people may not experience any side effects or only minor ones, it's essential to discuss any concerns with your doctor. If you experience any of the following side effects or any other unusual symptoms that bother you or do not go away, contact your doctor:

Dizziness or drowsiness
Thickening of mucus in the nose or throat
Feeling nervous or excitable
Upset stomach or vomiting

Reporting Side Effects

This list is not exhaustive, and you may experience other side effects not mentioned here. If you have questions or concerns about side effects, consult your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch. Your doctor can provide medical advice about side effects and help you manage any concerns.

Before Taking This Medication: Important Information to Share with Your Doctor

It is essential to inform your doctor about the following:

Any allergies you have, including allergies to this medication, its components, or other substances. Be sure to describe the symptoms you experienced.
If you are breastfeeding or plan to breastfeed, as you may need to avoid breastfeeding while taking this medication.
If the patient is a premature baby or newborn, as this form of the medication should not be given to them.

This medication may interact with other medications or health conditions. Therefore, it is crucial to provide your doctor and pharmacist with a comprehensive list of:

All prescription and over-the-counter medications you are taking
Any natural products or vitamins you are using
Your existing health problems

Your doctor will help you determine whether it is safe to take this medication with your other medications and health conditions. Do not start, stop, or change the dose of any medication without first consulting your doctor.

It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication.

To minimize the risk of severe side effects, adhere strictly to the dosage instructions provided by your doctor. Do not exceed the recommended dose, as this may increase your chance of experiencing severe side effects. Additionally, do not take this medication for a longer duration than prescribed by your doctor.

Until you are familiar with how this medication affects you, avoid operating a vehicle or engaging in any activities that require alertness.

Do not use this medication in conjunction with other products that contain diphenhydramine. It is also advisable to avoid consuming alcohol while taking this drug, as it may exacerbate side effects.

Before using marijuana, other forms of cannabis, or any prescription or over-the-counter (OTC) medications that may cause drowsiness, consult with your doctor to discuss potential interactions.

It is crucial to note that different brands of this medication may be suitable for children of varying ages. Therefore, consult with your doctor before administering this medication to a child. Furthermore, do not use this medication as a means to induce sleep in a child; instead, consult with your doctor for appropriate guidance.

If you are 60 years or older, exercise caution when using this medication, as you may be more susceptible to side effects. Similarly, when administering this medication to a child, use it with caution, as children may have a higher risk of experiencing excitability.

If you are pregnant or planning to become pregnant, inform your doctor, as it is necessary to discuss the benefits and risks associated with using this medication during pregnancy.

• Monoamine Oxidase Inhibitors (MAOIs) (concurrent use or within 14 days of MAOI discontinuation)

• Alcohol (additive CNS depression)
• Other CNS depressants (e.g., opioids, benzodiazepines, barbiturates, sedatives, hypnotics, anxiolytics, tricyclic antidepressants, antipsychotics) (additive CNS depression)
• Anticholinergic drugs (e.g., atropine, scopolamine, tricyclic antidepressants, some antipsychotics, benztropine) (additive anticholinergic effects, increased risk of urinary retention, constipation, dry mouth, blurred vision, confusion)
• Potassium chloride (wax matrix formulations) (increased risk of GI lesions due to anticholinergic-induced delayed gastric emptying)

• Beta-2 agonists (e.g., albuterol, salmeterol) (potential for additive anticholinergic effects, though less common)
• Cholinesterase inhibitors (e.g., donepezil, rivastigmine) (antagonism of therapeutic effect of cholinesterase inhibitors)
• Metoclopramide (antagonism of prokinetic effect)
• Topical anesthetics (e.g., pramoxine) (additive CNS depression if significant systemic absorption)

• Not available

• Drowsiness
• Dizziness
• Dry mouth
• Blurred vision
• Urinary retention
• Constipation
• Nausea
• Nervousness
• Paradoxical excitation (especially in children)
• Confusion (especially in elderly)

Generally considered low risk (Category B) for short-term, occasional use during pregnancy. However, long-term or high-dose use should be avoided. Always consult a healthcare provider.

L3 - Moderately safe. Diphenhydramine is excreted into breast milk. While generally considered compatible with breastfeeding for occasional use, it can cause drowsiness, irritability, or paradoxical excitation in the infant. It may also decrease milk supply due to its anticholinergic effects. Use with caution, especially in newborns or premature infants.

Not recommended for children under 6 years of age for cold/cough symptoms due to lack of efficacy and potential for serious side effects (e.g., respiratory depression, paradoxical excitation). Use with caution in older children, as they may experience paradoxical excitation (restlessness, nervousness, insomnia) rather than sedation. Dosing must be weight-based and carefully monitored.

Elderly patients are more susceptible to the anticholinergic side effects (e.g., dry mouth, blurred vision, urinary retention, constipation, confusion, falls) and sedative effects of diphenhydramine. Lower doses are often recommended, and alternative, less sedating antihistamines or non-pharmacologic options should be considered first. Use with extreme caution in patients with dementia or cognitive impairment.

• Diphenhydramine is a first-generation antihistamine with significant sedative and anticholinergic properties, making it useful for insomnia and motion sickness, but also contributing to its side effect profile.
• Advise patients to avoid activities requiring mental alertness (e.g., driving, operating machinery) after taking diphenhydramine.
• Warn patients about additive CNS depression when combined with alcohol or other sedatives.
• Be mindful of its anticholinergic effects, especially in elderly patients or those with pre-existing conditions like glaucoma, prostatic hypertrophy, or urinary retention.
• Paradoxical excitation (restlessness, nervousness) can occur, particularly in children and sometimes in the elderly.
• Not recommended for chronic insomnia; limit use to occasional sleeplessness.
• Consider second-generation antihistamines (e.g., loratadine, cetirizine, fexofenadine) for allergy relief when sedation is undesirable.

• For allergies: Second-generation antihistamines (e.g., loratadine, cetirizine, fexofenadine), nasal corticosteroids (e.g., fluticasone, mometasone), cromolyn sodium nasal spray.
• For insomnia: Melatonin, doxylamine, zolpidem, eszopiclone, ramelteon, cognitive behavioral therapy for insomnia (CBT-I).
• For motion sickness: Scopolamine (prescription patch), meclizine, dimenhydrinate.
• For cough: Dextromethorphan, guaifenesin, honey (for children >1 year).

If your symptoms or health issues persist or worsen, it's essential to contact your doctor for further guidance. To ensure your safety, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet, so be sure to check with your pharmacist for more information. If you have any questions or concerns about this medication, don't hesitate to reach out to your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek medical attention. When seeking help, be prepared to provide details about the overdose, including the medication taken, the amount, and the time it occurred.