M-Dryl 12.5/5ml 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
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 for short-term sleep problems or to help with coughs and motion sickness. 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 prescription and follow the instructions closely. You can take this medication with or without food, but if it causes stomach upset, take it with food to help minimize this side effect. When taking the liquid form of this medication, measure the dose carefully using the measuring device provided with the medication. If one is not provided, ask your pharmacist for a suitable measuring device.
If you have phenylketonuria (PKU), consult with 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 in a dry place. Avoid storing it in a bathroom. Do not freeze your medication. Keep all medications in a safe place, 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 by your pharmacist. If you have questions about disposing of your medication, consult with your pharmacist, who may be aware of 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 return to your regular dosing schedule. Do not take two doses at the same time or take extra doses. If you take this medication on an as-needed basis, 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 prescription and follow the instructions closely. You can take this medication with or without food, but if it causes stomach upset, take it with food to help minimize this side effect. When taking the liquid form of this medication, measure the dose carefully using the measuring device provided with the medication. If one is not provided, ask your pharmacist for a suitable measuring device.
If you have phenylketonuria (PKU), consult with 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 in a dry place. Avoid storing it in a bathroom. Do not freeze your medication. Keep all medications in a safe place, 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 by your pharmacist. If you have questions about disposing of your medication, consult with your pharmacist, who may be aware of 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 return to your regular dosing schedule. Do not take two doses at the same time or take extra doses. If you take this medication on an as-needed basis, do not take it more frequently than directed by your doctor.
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 medications that cause drowsiness (e.g., pain relievers, anxiety medications) while taking diphenhydramine, as this can increase sedation.
- Drink plenty of fluids and use sugar-free candies or gum to help with dry mouth.
- If using for motion sickness, take 30 minutes before travel.
- Do not use for more than 7-10 days for insomnia without consulting a doctor.
Available Forms & Alternatives
Available Strengths:
Dosing & Administration
Adult Dosing
Standard Dose:
25-50 mg orally every 4-6 hours as needed
Dose Range:
25 - 50 mg
Condition-Specific Dosing:
allergy:
25-50 mg orally every 4-6 hours (max 300 mg/day)
insomnia:
50 mg orally at bedtime
motionSickness:
25-50 mg orally 30 minutes before travel, then every 4-6 hours as needed
cough:
25 mg orally every 4 hours (max 150 mg/day)
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established (use with extreme caution, generally avoided in <2 years)
Child:
6-12 years: 12.5-25 mg orally every 4-6 hours (max 150 mg/day); 2-5 years: 6.25 mg orally every 4-6 hours (max 37.5 mg/day)
Adolescent:
12 years and older: 25-50 mg orally every 4-6 hours (max 300 mg/day)
Dose Adjustments
Renal Impairment:
Mild:
No specific adjustment needed, monitor for increased sedation.
Moderate:
Consider dose reduction (e.g., 25% reduction) or extended dosing interval.
Severe:
Consider significant dose reduction (e.g., 50% reduction) or extended dosing interval (e.g., every 8-12 hours).
Dialysis:
Diphenhydramine is not significantly removed by dialysis. Administer after dialysis on dialysis days. Monitor for increased sedation.
Hepatic Impairment:
Mild:
No specific adjustment needed, monitor for increased sedation.
Moderate:
Consider dose reduction (e.g., 25-50% reduction) or extended dosing interval.
Severe:
Consider significant dose reduction (e.g., 50% or more) or extended dosing interval due to reduced metabolism.
Confidence:
Medium
Pharmacology
Mechanism of Action
Diphenhydramine is a first-generation antihistamine that competitively blocks H1 histamine receptors in the periphery and CNS. It also possesses significant anticholinergic (muscarinic), antiemetic, and sedative properties due to its ability to cross the blood-brain barrier and affect central cholinergic receptors.
Pharmacokinetics
Absorption:
Bioavailability:
40-60%
Tmax:
1-4 hours
FoodEffect:
Food may slightly delay absorption but does not significantly affect bioavailability.
Distribution:
Vd:
17 L/kg
ProteinBinding:
78-85%
CnssPenetration:
Yes
Elimination:
HalfLife:
2.4-9.3 hours (average 4.3 hours in healthy adults; prolonged in elderly and those with hepatic/renal impairment)
Clearance:
Not available
ExcretionRoute:
Primarily renal (as metabolites)
Unchanged:
<1% (in urine)
Pharmacodynamics
OnsetOfAction:
15-60 minutes
PeakEffect:
1-3 hours
DurationOfAction:
4-6 hours
Confidence:
Medium
Safety & Warnings
Side Effects
Urgent Side Effects: Seek Medical Help Right Away
If you experience any of the following symptoms, call your doctor immediately or seek emergency medical attention, as they may be signs of a severe and potentially life-threatening reaction:
Allergic reaction symptoms, 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
Sudden change in balance
Feeling less alert than usual
Other Possible Side Effects
While many people may not experience any side effects or only mild ones, it's essential to be aware of the following potential side effects. If you experience any of these symptoms and they bother you or persist, 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 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.
If you experience any of the following symptoms, call your doctor immediately or seek emergency medical attention, as they may be signs of a severe and potentially life-threatening reaction:
Allergic reaction symptoms, 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
Sudden change in balance
Feeling less alert than usual
Other Possible Side Effects
While many people may not experience any side effects or only mild ones, it's essential to be aware of the following potential side effects. If you experience any of these symptoms and they bother you or persist, 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 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 breathing or wheezing
- Fast or irregular heartbeat
- Confusion, hallucinations, or unusual excitement (especially in children)
- Difficulty urinating
- Severe dry mouth or blurred vision
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 is not an exhaustive list of all potential interactions with this medication. Therefore, it is crucial to discuss the following with your doctor and pharmacist:
All medications you are currently taking, including prescription and over-the-counter drugs, natural products, and vitamins.
* Any health problems you have, as they may interact with this medication.
To ensure your safety, do not start, stop, or change the dose of any medication without first consulting your doctor. It is vital to verify that it is safe to take this medication with all 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 is not an exhaustive list of all potential interactions with this medication. Therefore, it is crucial to discuss the following with your doctor and pharmacist:
All medications you are currently taking, including prescription and over-the-counter drugs, natural products, and vitamins.
* Any health problems you have, as they may interact with this medication.
To ensure your safety, do not start, stop, or change the dose of any medication without first consulting your doctor. It is vital to verify that it is safe to take this medication with all 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, 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.
You should not use this medication in conjunction with other products that contain diphenhydramine. Furthermore, it is recommended 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 various ages. Therefore, before administering this drug to a child, consult with their doctor to ensure the appropriate brand and dosage are used. Moreover, this medication should not be used as a means to induce sleep in children; instead, consult with their doctor for alternative solutions.
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 drug 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 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, 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.
You should not use this medication in conjunction with other products that contain diphenhydramine. Furthermore, it is recommended 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 various ages. Therefore, before administering this drug to a child, consult with their doctor to ensure the appropriate brand and dosage are used. Moreover, this medication should not be used as a means to induce sleep in children; instead, consult with their doctor for alternative solutions.
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 drug 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 they will need to discuss the benefits and risks of using this medication during pregnancy with you.
Overdose Information
Overdose Symptoms:
- Severe drowsiness or coma
- Dilated pupils
- Flushed skin
- Dry mouth and skin
- Fever
- Agitation, confusion, hallucinations
- Seizures
- Arrhythmias (fast or irregular heartbeat)
- Urinary retention
- Respiratory depression
What to Do:
Seek immediate medical attention. Call 911 or Poison Control at 1-800-222-1222. Treatment is supportive and symptomatic, including activated charcoal if ingested recently, IV fluids, and benzodiazepines for seizures. Physostigmine may be used for severe anticholinergic toxicity but is generally reserved for life-threatening symptoms due to potential cardiac side effects.
Drug Interactions
Major Interactions
- Alcohol (increased CNS depression)
- Other CNS depressants (e.g., opioids, benzodiazepines, barbiturates, tricyclic antidepressants, sedatives, hypnotics) (additive CNS depression)
- Anticholinergic drugs (e.g., atropine, scopolamine, tricyclic antidepressants, phenothiazines) (additive anticholinergic effects, increased risk of urinary retention, constipation, dry mouth, blurred vision)
- Monoamine Oxidase Inhibitors (MAOIs) (prolonged and intensified anticholinergic and CNS depressant effects)
Moderate Interactions
- Potassium chloride (oral) (increased risk of GI lesions due to anticholinergic-induced delayed gastric emptying)
- Metoclopramide (antagonism of prokinetic effect)
- Cholinesterase inhibitors (e.g., donepezil, rivastigmine) (antagonism of therapeutic effect)
Minor Interactions
- Betahistine (antagonism of effect)
Monitoring
Baseline Monitoring
Patient history (allergies, existing medical conditions like glaucoma, BPH, asthma, heart disease)
Rationale: To identify contraindications or conditions where caution is needed due to anticholinergic effects or respiratory depression risk.
Timing: Before initiation
Concomitant medications (especially CNS depressants, anticholinergics, MAOIs)
Rationale: To identify potential drug interactions leading to excessive sedation or anticholinergic effects.
Timing: Before initiation
Routine Monitoring
Level of sedation/drowsiness
Frequency: Daily, especially during initial therapy or dose changes
Target: Acceptable level of drowsiness for intended use (e.g., sleep) without excessive impairment for daily activities (if used for allergy)
Action Threshold: Excessive sedation, inability to perform daily tasks, or impaired consciousness; consider dose reduction or discontinuation.
Anticholinergic side effects (dry mouth, blurred vision, urinary retention, constipation)
Frequency: Daily, as needed
Target: Minimal to no bothersome symptoms
Action Threshold: Severe or bothersome symptoms; consider dose reduction or alternative therapy.
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 (Category B). However, use with caution, especially in the third trimester, as it may cause uterine contractions or neonatal withdrawal symptoms if used chronically.
Trimester-Specific Risks:
First Trimester:
Low risk of teratogenicity.
Second Trimester:
Generally considered safe for occasional use.
Third Trimester:
Use with caution; chronic use may lead to uterine contractions or neonatal withdrawal symptoms (e.g., tremors, irritability).
Lactation
Excreted into breast milk. Generally considered compatible with breastfeeding for occasional use, but monitor infant for drowsiness, irritability, or anticholinergic effects (e.g., dry mouth, constipation). Avoid regular or high-dose use, especially in newborns or premature infants.
Infant Risk:
L3 (Moderately safe - possible mild effects on infant or milk supply)
Pediatric Use
Use with caution, especially in children under 2 years of age, due to increased risk of respiratory depression and paradoxical excitation (nervousness, restlessness, hallucinations). Dosage must be carefully calculated by weight/age. Avoid use as a sedative in infants.
Geriatric Use
Elderly patients are more susceptible to the anticholinergic side effects (e.g., confusion, delirium, urinary retention, constipation, dry mouth, blurred vision) and sedative effects. Use lower doses and monitor closely. Avoid use in elderly patients with dementia or cognitive impairment due to increased risk of adverse cognitive effects.
Clinical Information
Clinical Pearls
- 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.
- It is often misused as a primary sleep aid; however, its efficacy for chronic insomnia is limited, and tolerance to its sedative effects can develop quickly.
- Paradoxical excitation (restlessness, agitation) can occur, especially in young children and occasionally in adults.
- Due to its anticholinergic effects, it should be used with caution or avoided in patients with narrow-angle glaucoma, prostatic hypertrophy, bladder neck obstruction, or severe constipation.
- Avoid concomitant use with alcohol or other CNS depressants due to additive sedative effects.
- The 'M-Dryl 12.5/5ml Liquid' formulation indicates a concentration of 12.5 mg of diphenhydramine per 5 ml, which is a common pediatric and lower adult dose.
Alternative Therapies
- Second-generation antihistamines (e.g., loratadine, cetirizine, fexofenadine) for allergy symptoms (less sedating)
- Melatonin, doxylamine, or zolpidem for insomnia (different mechanisms)
- Meclizine or scopolamine for motion sickness (less sedating or different mechanism)
- Dextromethorphan or guaifenesin for cough (non-sedating antitussives/expectorants)
Cost & Coverage
Average Cost:
$5 - $20 per 120-240 ml liquid
Generic Available:
Yes
Insurance Coverage:
Tier 1 (most insurance plans cover generic diphenhydramine)
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 information. 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 emergency medical attention. When seeking help, be prepared to provide details about the medication taken, the amount, and the time it happened.