Diphenhydramine 12.5mg/5ml Liquid
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, Antiemetic
Pharmacologic Class
First-generation H1-receptor antagonist
Pregnancy Category
Category B
FDA Approved
Jan 1970
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 help with insomnia (trouble sleeping) because it causes drowsiness. It works by blocking a natural substance in your body called histamine.
How to Use This Medicine
Taking Your Medication Correctly
To use this medication safely and effectively, follow your doctor's instructions and read all the information provided. Take your medication with or without food, but if it causes stomach upset, take it with food to help minimize discomfort. When taking a liquid dose, measure it carefully using the measuring device that comes with the medication. If one is not provided, ask your pharmacist for a suitable measuring device.
If you have phenylketonuria (PKU), consult your doctor before taking this medication, as some products 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. To ensure safety, keep all medications out of the reach of children and pets.
When disposing of unused or expired medication, do not flush it down the toilet or pour it down the drain unless instructed to do so. Instead, ask your pharmacist about the best way to dispose of your medication. 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 basis and miss a dose, take it as soon as you remember. However, if it is 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, follow your doctor's instructions and do not take it more frequently than recommended.
To use this medication safely and effectively, follow your doctor's instructions and read all the information provided. Take your medication with or without food, but if it causes stomach upset, take it with food to help minimize discomfort. When taking a liquid dose, measure it carefully using the measuring device that comes with the medication. If one is not provided, ask your pharmacist for a suitable measuring device.
If you have phenylketonuria (PKU), consult your doctor before taking this medication, as some products 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. To ensure safety, keep all medications out of the reach of children and pets.
When disposing of unused or expired medication, do not flush it down the toilet or pour it down the drain unless instructed to do so. Instead, ask your pharmacist about the best way to dispose of your medication. 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 basis and miss a dose, take it as soon as you remember. However, if it is 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, follow your doctor's instructions and do not take it more frequently than recommended.
Lifestyle & Tips
- Avoid driving or operating heavy machinery until you know how this medication affects you, as it can cause significant drowsiness.
- Avoid alcohol and other sedatives while taking this medication, as they can increase drowsiness and other side effects.
- Drink plenty of fluids to help with dry mouth.
- If using 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) every 4-6 hours as needed
Dose Range:
25 - 50 mg
Condition-Specific Dosing:
insomnia:
50 mg (20 ml) at bedtime
motion_sickness:
25-50 mg (10-20 ml) 30 minutes before exposure, then every 4-6 hours as needed
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established (generally not recommended under 2 years without physician guidance)
Child:
2-5 years: 6.25 mg (2.5 ml) every 4-6 hours (Max 37.5 mg/day); 6-11 years: 12.5-25 mg (5-10 ml) every 4-6 hours (Max 150 mg/day)
Adolescent:
12 years and older: 25-50 mg (10-20 ml) every 4-6 hours (Max 300 mg/day)
Dose Adjustments
Renal Impairment:
Mild:
No specific adjustment recommended, use with caution.
Moderate:
Consider dose reduction or extended dosing interval (e.g., every 6-8 hours).
Severe:
Consider significant dose reduction or extended dosing interval (e.g., every 8-12 hours).
Dialysis:
Diphenhydramine is not significantly removed by hemodialysis. Administer after dialysis if needed.
Hepatic Impairment:
Mild:
No specific adjustment recommended, use with caution.
Moderate:
Consider dose reduction or extended dosing interval.
Severe:
Consider significant dose reduction or extended dosing interval due to reduced metabolism.
Pharmacology
Mechanism of Action
Diphenhydramine is a first-generation antihistamine that competitively antagonizes H1 histamine receptors, thereby blocking the effects of histamine. It also possesses significant anticholinergic (muscarinic), antiemetic, and sedative properties due to its ability to cross the blood-brain barrier and affect central H1 and muscarinic receptors.
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:
17 L/kg
ProteinBinding:
78-99%
CnssPenetration:
Yes
Elimination:
HalfLife:
2.4-9.3 hours (average 4.3 hours)
Clearance:
Not available
ExcretionRoute:
Primarily renal (urine)
Unchanged:
<1%
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 do not go away, contact your doctor for advice:
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. 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 do not go away, contact your doctor for advice:
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. 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 (especially in children or elderly)
- Seizures
- Signs of an allergic reaction (rash, itching, swelling, severe dizziness, trouble breathing)
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. Be sure to describe the allergic reaction and its symptoms.
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 health problems, including any medical conditions or concerns
Before starting, stopping, or changing the dose of any medication, including this one, consult with your doctor to ensure your safety. They will help you determine if it is safe to take this medication with your other medications and health conditions.
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 allergic reaction and its symptoms.
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 health problems, including any medical conditions or concerns
Before starting, stopping, or changing the dose of any medication, including this one, consult with your doctor to ensure your safety. They will help you determine if it is safe to take this medication with your other medications and health conditions.
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 severe side effects. Additionally, do not take this medication for a longer period than specified by your doctor.
Until you are aware of how this medication affects you, avoid operating a vehicle and engaging in other 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. Therefore, it is crucial to consult with a doctor before administering this medication to a child. Furthermore, do not use this medication as a means to induce sleep in a child; instead, discuss alternative options with your 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 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 potential benefits and risks associated with using this medication during pregnancy.
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 severe side effects. Additionally, do not take this medication for a longer period than specified by your doctor.
Until you are aware of how this medication affects you, avoid operating a vehicle and engaging in other 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. Therefore, it is crucial to consult with a doctor before administering this medication to a child. Furthermore, do not use this medication as a means to induce sleep in a child; instead, discuss alternative options with your 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 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 potential benefits and risks associated with using this medication during pregnancy.
Overdose Information
Overdose Symptoms:
- Severe drowsiness or coma
- Dilated pupils
- Flushed skin
- Dry mouth and skin
- Fever
- Hallucinations
- Agitation, restlessness, or delirium
- Ataxia (loss of coordination)
- Seizures
- Tachycardia (fast heart rate)
- Arrhythmias
- Urinary retention
- Respiratory depression
What to Do:
Call 911 or Poison Control immediately (1-800-222-1222). Seek emergency medical attention. Treatment is supportive and may include activated charcoal, IV fluids, and benzodiazepines for seizures or agitation. Physostigmine may be used for severe anticholinergic toxicity.
Drug Interactions
Contraindicated Interactions
- Not available
Major Interactions
- CNS depressants (e.g., alcohol, benzodiazepines, opioids, sedatives, hypnotics): Increased sedation and respiratory depression.
- MAO inhibitors (MAOIs): Increased anticholinergic effects and CNS depression. Avoid concomitant use or within 14 days of MAOI discontinuation.
- Other anticholinergic drugs (e.g., tricyclic antidepressants, atropine, some antipsychotics): Increased risk of anticholinergic side effects (dry mouth, blurred vision, urinary retention, constipation, confusion).
Moderate Interactions
- Potassium chloride (oral forms): Increased risk of GI lesions due to anticholinergic-induced delayed gastric emptying.
- Cholinesterase inhibitors (e.g., donepezil, rivastigmine): Antagonism of therapeutic effects of cholinesterase inhibitors.
- Metoclopramide: Antagonism of prokinetic effects.
Minor Interactions
- Betahistine: Potential antagonism of betahistine's effects.
Monitoring
Baseline Monitoring
Patient history (allergies, existing medical conditions, current medications)
Rationale: To identify contraindications, potential drug interactions, and conditions that may be exacerbated by diphenhydramine (e.g., glaucoma, BPH, asthma).
Timing: Prior to initiation of therapy
Routine Monitoring
Symptom relief and adverse effects (e.g., drowsiness, dry mouth, blurred vision, urinary retention)
Frequency: During therapy, especially with initial doses or dose changes
Target: Adequate symptom control with tolerable side effects
Action Threshold: Persistent or severe adverse effects, lack of efficacy
Symptom Monitoring
- Drowsiness/Sedation
- Dizziness
- Dry mouth
- Blurred vision
- Urinary retention
- Constipation
- Nausea/Vomiting
- Paradoxical excitation (especially in children)
- Confusion/Delirium (especially in elderly)
Special Patient Groups
Pregnancy
Generally considered low risk (Category B). Studies in animals have not shown harm, and human data suggest no increased risk of major birth defects. However, use only if clearly needed and benefits outweigh risks.
Trimester-Specific Risks:
First Trimester:
No clear evidence of increased risk of major birth defects.
Second Trimester:
Generally considered safe for occasional use.
Third Trimester:
Use with caution near term, as it may cause drowsiness or irritability in the newborn, or uterine contractions due to anticholinergic effects.
Lactation
Excreted into breast milk. Use is generally discouraged, especially in newborns or preterm infants, due to potential for infant drowsiness, irritability, and theoretical risk of decreased milk supply (due to anticholinergic effects). If used, observe infant for sedation or excitation.
Infant Risk:
Risk L3 (Moderately Safe) - potential for infant drowsiness, irritability, and theoretical risk of decreased milk supply. Consider alternative if possible, or use lowest effective dose for shortest duration.
Pediatric Use
Not recommended for children under 2 years of age for cough/cold symptoms due to lack of efficacy and potential for serious side effects, including respiratory depression and paradoxical excitation. Use with caution and strict adherence to weight-based dosing in older children. Paradoxical excitation (restlessness, nervousness, insomnia) can occur.
Geriatric Use
Increased susceptibility to anticholinergic side effects (e.g., dry mouth, blurred vision, urinary retention, constipation, confusion, dizziness, falls). Use with caution and consider lower doses. Avoid in elderly patients with dementia due to increased risk of cognitive impairment and delirium.
Clinical Information
Clinical Pearls
- Diphenhydramine is a highly sedating antihistamine; advise patients about impaired ability to drive or operate machinery.
- It has significant anticholinergic effects, which can be problematic in elderly patients or those with conditions like glaucoma, BPH, or constipation.
- Paradoxical excitation (restlessness, agitation) can occur, especially in young children and occasionally in the elderly.
- Often used off-label for insomnia due to its sedative properties, but tolerance to the sedative effect can develop quickly.
- Avoid use for cough/cold symptoms in children under 2 years of age as per FDA recommendations.
- Can cause photosensitivity; advise patients to use sun protection.
Alternative Therapies
- For allergies: Second-generation antihistamines (e.g., loratadine, cetirizine, fexofenadine) which are less sedating and have fewer anticholinergic effects.
- For insomnia: Melatonin, doxylamine, zolpidem (prescription), non-pharmacological interventions (sleep hygiene).
- For cough: Dextromethorphan, guaifenesin (for productive cough).
- For nausea/vomiting: Dimenhydrinate (similar to diphenhydramine), ondansetron, promethazine.
Cost & Coverage
Average Cost:
$5 - $20 per 120-240 ml bottle
Generic Available:
Yes
Insurance Coverage:
Tier 1 (Generic)
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.