Diphenhydramine 12.5mg/5ml Elixir
It is used to relieve coughing.It is used to ease allergy signs.It is used to help motion sickness.It is used to treat signs like Parkinson's disease caused by other health problems. It is used to treat sleep problems.
Drug Class
Antihistamine, Sedative, Antitussive
Pharmacologic Class
First-generation H1-receptor antagonist
Pregnancy Category
Category B
FDA Approved
Mar 1946
DEA Schedule
Not Controlled
Overview
What is this medicine?
Diphenhydramine is an antihistamine that helps relieve allergy symptoms like sneezing, runny nose, and itchy eyes. It can also make you feel sleepy, so it's often used to help with occasional sleeplessness. It works by blocking a natural substance in your body called histamine.
How to Use This Medicine
Taking Your Medication Correctly
To ensure you get the most benefit from your medication, follow your doctor's instructions carefully. Read all the information provided with your medication and follow the instructions closely. You can take this medication with or without food. If it causes stomach upset, take it with food to help minimize this side effect. When taking the liquid form of this medication, measure your dose carefully using the measuring device that comes with the medication. If no device is provided, ask your pharmacist for a suitable measuring device.
If you have phenylketonuria (PKU), consult your doctor before taking this medication, as some products may contain phenylalanine.
Storing and Disposing of Your Medication
Store your medication at room temperature, protected from light and moisture. Keep it in a dry place, away from the bathroom. Do not freeze your medication. Keep all medications in a safe location, out of the reach of children and pets. Dispose of unused or expired medications properly. Do not flush them down the toilet or pour them down the drain unless instructed to do so. If you have questions about disposing of your medication, consult your pharmacist. You may also want to check if there are any drug take-back programs in your area.
What to Do If You Miss a Dose
If you take this medication on a regular schedule, take the missed dose as soon as you remember. However, if it's close to the time for your next dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses. If you take this medication as needed, do not take it more frequently than directed by your doctor.
To ensure you get the most benefit from your medication, follow your doctor's instructions carefully. Read all the information provided with your medication and follow the instructions closely. You can take this medication with or without food. If it causes stomach upset, take it with food to help minimize this side effect. When taking the liquid form of this medication, measure your dose carefully using the measuring device that comes with the medication. If no device is provided, ask your pharmacist for a suitable measuring device.
If you have phenylketonuria (PKU), consult your doctor before taking this medication, as some products may contain phenylalanine.
Storing and Disposing of Your Medication
Store your medication at room temperature, protected from light and moisture. Keep it in a dry place, away from the bathroom. Do not freeze your medication. Keep all medications in a safe location, out of the reach of children and pets. Dispose of unused or expired medications properly. Do not flush them down the toilet or pour them down the drain unless instructed to do so. If you have questions about disposing of your medication, consult your pharmacist. You may also want to check if there are any drug take-back programs in your area.
What to Do If You Miss a Dose
If you take this medication on a regular schedule, take the missed dose as soon as you remember. However, if it's close to the time for your next dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses. If you take this medication as needed, do not take it more frequently than directed by your doctor.
Lifestyle & Tips
- Do not drive or operate heavy machinery until you know how this medication affects you, as it can cause significant drowsiness.
- Avoid alcohol and other sedating medications while taking diphenhydramine, as this can increase drowsiness and other side effects.
- Take with food or milk if stomach upset occurs.
- Use caution in hot weather or during exercise, as this medication can reduce sweating and increase the risk of heatstroke.
- For sleep, take about 30 minutes before bedtime.
Available Forms & Alternatives
Available Strengths:
- Diphenhydramine 50mg/ml Inj, 1ml
- Diphenhydramine Hcl 50mg Caps
- Diphenhydramine 50mg Capsules
- Diphenhydramine 12.5mg/5ml Elixir
- Diphenhydramine 25mg Tablets
- Diphenhydramine 25mg/10ml Liquid
- Diphenhydramine 12.5mg/5ml Liquid
- Diphenhydramine 12.5mg/5ml Liquid
- Diphenhydramine 25mg Caps
- Diphenhydramine 25mg Capsules
- Diphenhydramine 50mg/ml Inj, 1ml
- Diphenhydramine 25mg Tablets
- Diphenhydramine 25mg Capsules
Dosing & Administration
Adult Dosing
Standard Dose:
25-50 mg (10-20 mL) orally every 4-6 hours as needed
Dose Range:
25 - 50 mg
Condition-Specific Dosing:
allergy:
25-50 mg (10-20 mL) every 4-6 hours
insomnia:
50 mg (20 mL) at bedtime
motion_sickness:
25-50 mg (10-20 mL) 30 minutes before travel, then every 4-6 hours as needed
Pediatric Dosing
Neonatal:
Not established (contraindicated in premature infants and neonates)
Infant:
Not established (contraindicated in infants <2 years old without physician supervision)
Child:
2 to <6 years: 6.25 mg (2.5 mL) orally every 4-6 hours, max 37.5 mg/day (15 mL/day); 6 to <12 years: 12.5-25 mg (5-10 mL) orally every 4-6 hours, max 150 mg/day (60 mL/day)
Adolescent:
12 years and older: 25-50 mg (10-20 mL) orally every 4-6 hours, max 300 mg/day (120 mL/day)
Dose Adjustments
Renal Impairment:
Mild:
No specific adjustment generally needed, monitor for increased sedation.
Moderate:
Consider dose reduction (e.g., 25% to 50%) or extended dosing interval (e.g., every 6-8 hours).
Severe:
Significant dose reduction (e.g., 50% or more) or extended dosing interval (e.g., every 8-12 hours) recommended due to prolonged half-life.
Dialysis:
Not significantly removed by hemodialysis. Administer after dialysis on dialysis days. Monitor for increased sedation.
Hepatic Impairment:
Mild:
No specific adjustment generally needed.
Moderate:
Consider dose reduction (e.g., 25% to 50%) or extended dosing interval (e.g., every 6-8 hours) due to impaired metabolism.
Severe:
Significant dose reduction (e.g., 50% or more) or extended dosing interval (e.g., every 8-12 hours) recommended due to impaired metabolism.
Pharmacology
Mechanism of Action
Diphenhydramine is a first-generation antihistamine that competitively antagonizes H1-receptors in the periphery and CNS, preventing histamine from binding. This action reduces allergic symptoms like sneezing, itching, and rhinorrhea. Its ability to cross the blood-brain barrier contributes to its sedative effects. It also possesses significant anticholinergic (antimuscarinic) properties, which contribute to its drying effects (e.g., reducing nasal secretions) and some of its side effects (e.g., dry mouth, blurred vision).
Pharmacokinetics
Absorption:
Bioavailability:
40-60%
Tmax:
1-4 hours
FoodEffect:
Food may slightly delay absorption but does not significantly affect the extent of absorption.
Distribution:
Vd:
3.3-6.8 L/kg
ProteinBinding:
78-99%
CnssPenetration:
Yes
Elimination:
HalfLife:
2.4-9.3 hours (average 4-8 hours)
Clearance:
Not available
ExcretionRoute:
Renal (primarily as metabolites)
Unchanged:
<1% (in urine)
Pharmacodynamics
OnsetOfAction:
15-60 minutes
PeakEffect:
1-3 hours
DurationOfAction:
4-6 hours
Safety & Warnings
Side Effects
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 persist, contact your doctor for guidance:
Dizziness or drowsiness
Thickening of mucus in the nose or throat
Feeling nervous or excitable
Upset stomach or vomiting
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.
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 persist, contact your doctor for guidance:
Dizziness or drowsiness
Thickening of mucus in the nose or throat
Feeling nervous or excitable
Upset stomach or vomiting
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.
Seek Immediate Medical Attention If You Experience:
- Severe drowsiness or dizziness
- Difficulty urinating
- Blurred vision or eye pain
- Fast or irregular heartbeat
- Confusion or hallucinations
- Seizures
- Paradoxical excitation (restlessness, nervousness, hyperactivity, especially in children)
Before Using This Medicine
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, such as foods or drugs. 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. To ensure safe use, it is crucial to:
Inform your doctor and pharmacist about all medications you are taking, including prescription and over-the-counter drugs, natural products, and vitamins.
Discuss all your health problems with your doctor.
Verify that it is safe to take this medication with your other medications and health conditions.
* Never start, stop, or change the dose of any medication without consulting 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, such as foods or drugs. 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. To ensure safe use, it is crucial to:
Inform your doctor and pharmacist about all medications you are taking, including prescription and over-the-counter drugs, natural products, and vitamins.
Discuss all your health problems with your doctor.
Verify that it is safe to take this medication with your other medications and health conditions.
* Never start, stop, or change the dose of any medication without consulting your doctor.
Precautions & Cautions
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, do not exceed the dosage prescribed by your doctor. Taking more than the recommended amount can increase your chance of experiencing serious adverse effects. Additionally, do not take this medication for a longer period than instructed by your doctor.
Until you understand how this medication affects you, avoid operating a vehicle or engaging in activities that require alertness.
Do not use this medication in conjunction with other products containing diphenhydramine. It is also recommended to avoid consuming alcohol while taking this drug.
Before using marijuana, other forms of cannabis, or prescription and over-the-counter (OTC) medications that may cause drowsiness, consult with your doctor.
Note that different brands of this medication may be suitable for children of varying ages. Prior to administering this medication to a child, consult with their doctor. Furthermore, do not use this medication as a means to induce sleep in children; instead, discuss alternative solutions with their doctor.
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 children, use it with caution, as they may have a higher risk of experiencing excitability.
If you are pregnant or plan to become pregnant, inform your doctor, as they will need to discuss the benefits and risks of using this medication during pregnancy with you.
To minimize the risk of severe side effects, do not exceed the dosage prescribed by your doctor. Taking more than the recommended amount can increase your chance of experiencing serious adverse effects. Additionally, do not take this medication for a longer period than instructed by your doctor.
Until you understand how this medication affects you, avoid operating a vehicle or engaging in activities that require alertness.
Do not use this medication in conjunction with other products containing diphenhydramine. It is also recommended to avoid consuming alcohol while taking this drug.
Before using marijuana, other forms of cannabis, or prescription and over-the-counter (OTC) medications that may cause drowsiness, consult with your doctor.
Note that different brands of this medication may be suitable for children of varying ages. Prior to administering this medication to a child, consult with their doctor. Furthermore, do not use this medication as a means to induce sleep in children; instead, discuss alternative solutions with their doctor.
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 children, use it with caution, as they may have a higher risk of experiencing excitability.
If you are pregnant or plan to become pregnant, inform your doctor, as they will need to discuss the benefits and risks of using this medication during pregnancy with you.
Overdose Information
Overdose Symptoms:
- Severe drowsiness or deep sleep
- Severe dry mouth, nose, or throat
- Flushing (redness of the face)
- Dilated pupils
- Blurred vision
- Hallucinations
- Confusion
- Agitation
- Seizures
- Loss of consciousness
- Coma
- Respiratory depression
- Cardiac arrhythmias
What to Do:
Seek immediate medical attention. Call 911 or Poison Control at 1-800-222-1222. Treatment is supportive and may include activated charcoal, gastric lavage, and management of symptoms (e.g., benzodiazepines for seizures, physostigmine for severe anticholinergic toxicity under medical supervision).
Drug Interactions
Contraindicated Interactions
- Monoamine Oxidase Inhibitors (MAOIs) (concurrent use or within 14 days of MAOI discontinuation)
Major Interactions
- CNS depressants (e.g., alcohol, opioids, benzodiazepines, sedatives, hypnotics, tricyclic antidepressants, other antihistamines): Increased sedation and CNS depression.
- Anticholinergic drugs (e.g., tricyclic antidepressants, atropine, some antipsychotics): Increased risk of anticholinergic side effects (dry mouth, blurred vision, urinary retention, constipation).
Moderate Interactions
- Potassium chloride (oral forms): Increased risk of gastrointestinal lesions due to anticholinergic-induced delayed gastric emptying.
- Betahistine: Diphenhydramine may antagonize the effects of betahistine.
Minor Interactions
- Acetylcholinesterase inhibitors (e.g., donepezil, rivastigmine): Diphenhydramine's anticholinergic effects may reduce the efficacy of these drugs.
Monitoring
Baseline Monitoring
Patient history (allergies, existing medical conditions like glaucoma, prostatic hypertrophy, asthma, thyroid disease)
Rationale: To identify contraindications or conditions requiring caution.
Timing: Prior to initiation
Current medication list
Rationale: To identify potential drug-drug interactions, especially with CNS depressants or anticholinergic agents.
Timing: Prior to initiation
Routine Monitoring
Level of sedation/drowsiness
Frequency: Daily, especially during initial use
Target: Acceptable level of drowsiness for intended use (e.g., sleep) without excessive impairment for other activities.
Action Threshold: Excessive sedation, inability to perform daily tasks, or impaired alertness; consider dose reduction or discontinuation.
Anticholinergic side effects (dry mouth, blurred vision, urinary retention, constipation)
Frequency: Daily, as needed
Target: Minimal to tolerable discomfort
Action Threshold: Severe or intolerable side effects; consider dose reduction or discontinuation.
Symptom Monitoring
- Drowsiness
- Dizziness
- Dry mouth
- Blurred vision
- Urinary retention
- Constipation
- Nausea
- Vomiting
- Nervousness
- Paradoxical excitation (especially in children)
- Confusion (especially in elderly)
Special Patient Groups
Pregnancy
Generally considered safe for occasional use during pregnancy, particularly in the second and third trimesters. However, use should be limited to the lowest effective dose for the shortest duration. Consult a healthcare provider before use.
Trimester-Specific Risks:
First Trimester:
Limited data, but no consistent evidence of increased risk of major birth defects. Use with caution.
Second Trimester:
Generally considered safe for occasional use.
Third Trimester:
Generally considered safe for occasional use. Avoid use close to term as it may cause irritability or tremors in the neonate.
Lactation
Excreted into breast milk. Use with caution, especially in nursing infants, as it may cause drowsiness, irritability, or paradoxical excitation in the infant. May also decrease milk supply due to anticholinergic effects.
Infant Risk:
Low to moderate risk. Monitor infant for sedation, irritability, or poor feeding. Avoid use in premature or jaundiced infants.
Pediatric Use
Use with extreme caution in children, especially those under 2 years of age, due to increased risk of respiratory depression, paradoxical excitation, and anticholinergic effects. Dosing must be precise based on age/weight. Not recommended for use as a sedative in children under 2 years without physician supervision. Overdose can be fatal.
Geriatric Use
Elderly patients are more susceptible to the sedative and anticholinergic side effects (e.g., confusion, dizziness, dry mouth, urinary retention, constipation, falls). Use the lowest effective dose and monitor closely. Avoid use in elderly patients with dementia or cognitive impairment due to increased risk of delirium.
Clinical Information
Clinical Pearls
- Diphenhydramine is a first-generation antihistamine known for its significant sedative and anticholinergic effects.
- It is commonly used for allergic reactions, insomnia, and motion sickness.
- Caution is advised in pediatric patients due to the risk of paradoxical excitation and in geriatric patients due to increased sensitivity to anticholinergic effects and sedation, increasing fall risk.
- Avoid concurrent use with alcohol or other CNS depressants.
- Patients should be advised against driving or operating machinery after taking diphenhydramine.
- The anticholinergic effects can lead to dry mouth, blurred vision, urinary retention, and constipation.
Alternative Therapies
- Second-generation antihistamines (e.g., loratadine, cetirizine, fexofenadine) for allergy symptoms (less sedating).
- Doxylamine (another sedating antihistamine) for insomnia.
- Melatonin for insomnia.
- Meclizine or scopolamine for motion sickness.
- Nasal corticosteroids or decongestants for allergic rhinitis.
Cost & Coverage
Average Cost:
$5 - $20 per 120-240 mL bottle
Generic Available:
Yes
Insurance Coverage:
Tier 1 (Generic, often OTC and not covered by prescription plans unless prescribed)
General Drug Facts
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 details. If you have any questions or concerns about your 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 information about the medication taken, the amount, and the time it happened.