Do not take diphenhydramine and phenylephrine if you have taken selegiline (Carbex, Eldepryl) or a monoamine oxidase inhibitor (MAOI) such as isocarboxazid (Marplan), phenelzine (Nardil), or tranylcypromine (Parnate) in the last 14 days. A dangerous drug interaction could occur, leading to serious side effects.
Before taking this medication, tell your doctor if you have
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epilepsy or another seizure disorder;
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been diagnosed with sleep apnea (periods of not breathing during sleep);
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thyroid problems;
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asthma, emphysema, or chronic obstructive pulmonary disease (COPD);
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gallbladder disease;
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a head injury;
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Addison’s disease;
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diabetes;
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glaucoma;
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an ulcer or an obstruction in the stomach;
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bladder problems or difficulty urinating;
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an enlarged prostate;
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high blood pressure, irregular heartbeats, or any type of heart disease;
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kidney problems; or
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liver problems.
You may not be able to take diphenhydramine and phenylephrine, or you may require a dosage adjustment or special monitoring during treatment if you have any of the conditions listed above.
It is not known whether diphenhydramine and phenylephrine will be harmful to an unborn baby. Do not take this medication without first talking to your doctor if you are pregnant or could become pregnant during treatment.
This medication may pass into breast milk and be harmful to a nursing infant. Do not take this medication without first talking to your doctor if you are breast-feeding a baby.
If you are over 60 years of age, you may be more likely to experience side effects from diphenhydramine and phenylephrine. Your doctor may prescribe a lower dose of this medication.
Consult your doctor or pharmacist before treating a child with this medication. Children are more susceptible than adults to the effects of medicines and may have unusual reactions. Read the package label for directions for use in children.
Take diphenhydramine and phenylephrine exactly as directed. If you do not understand these directions, ask your pharmacist, nurse, or doctor to explain them to you.
To ensure that you get a correct dose, measure the liquid form of diphenhydramine and phenylephrine with a special dose-measuring spoon or cup, not with a regular table spoon. If you do not have a dose-measuring device, ask your pharmacist where you can get one.
Do not take more of this medication than is recommended. An overdose of this medication can cause serious harm.
Do not take diphenhydramine and phenylephrine for longer than is prescribed. If your symptoms do not improve, if they get worse, or if they are accompanied by fever, talk to your doctor.
Store diphenhydramine and phenylephrine at room temperature away from moisture and heat.
Take the missed dose as soon as you remember. However, if it is almost time for the next
dose, skip the missed dose and take only the next regularly scheduled dose.
If you experience any of the following uncommon but serious side effects, stop taking diphenhydramine and phenylephrine and seek emergency medical attention or contact your doctor immediately:
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an allergic reaction (difficulty breathing; closing of the throat; swelling of the lips, tongue, or face; or hives); or
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confusion, hallucinations, or unusual behavior.
Other, less serious side effects may be more likely to occur. Continue to take diphenhydramine and phenylephrine and talk to your doctor if you experience
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dryness of the eyes, nose, and mouth;
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drowsiness or dizziness;
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blurred vision;
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difficulty urinating; or
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excitation in children.
Side effects other than those listed here may also occur. Talk to your doctor about any side effect that seems unusual or that is especially bothersome.
Use caution when driving, operating machinery, or performing other hazardous activities. Diphenhydramine and phenylephrine may cause dizziness or drowsiness. If you experience dizziness or drowsiness, avoid these activities.
Use alcohol cautiously. Alcohol may increase drowsiness and dizziness while you are taking diphenhydramine and phenylephrine.
Use caution when driving, operating machinery, or performing other hazardous activities. Diphenhydramine and phenylephrine may cause dizziness or drowsiness. If you experience dizziness or drowsiness, avoid these activities.
Use alcohol cautiously. Alcohol may increase drowsiness and dizziness while you are taking diphenhydramine and phenylephrine.
Do not take other over-the-counter cough, cold, allergy, diet, or sleep aids while taking diphenhydramine and phenylephrine without first talking to your doctor or pharmacist. Other medications may also contain diphenhydramine, phenylephrine or other similar drugs. You may accidentally take too much of these medicines.
Diphenhydramine and phenylephrine may increase the effects of other drugs that cause drowsiness, including antidepressants, alcohol, other antihistamines, pain relievers, anxiety medicines, seizure medicines, and muscle relaxants. Dangerous sedation, dizziness, or drowsiness may occur if diphenhydramine and phenylephrine is taken with any of these medications.
Do not take diphenhydramine and phenylephrine if you have taken selegiline (Carbex, Eldepryl) or a monoamine oxidase inhibitor (MAOI) such as isocarboxazid (Marplan), phenelzine (Nardil), or tranylcypromine (Parnate) in the last 14 days. A dangerous drug interaction could occur, leading to serious side effects.
Do not take other over-the-counter cough, cold, allergy, diet, or sleep aids while taking diphenhydramine and phenylephrine without first talking to your doctor or pharmacist. Other medications may also contain diphenhydramine, phenylephrine or other similar drugs. You may accidentally take too much of these medicines.
Diphenhydramine and phenylephrine may increase the effects of other drugs that cause drowsiness, including antidepressants, alcohol, other antihistamines, pain relievers, anxiety medicines, seizure medicines, and muscle relaxants. Dangerous sedation, dizziness, or drowsiness may occur if diphenhydramine and phenylephrine is taken with any of these medications.
Drugs other than those listed here may also interact with diphenhydramine and phenylephrine. Talk to your doctor and pharmacist before taking any prescription or over-the-counter medicines, including vitamins, minerals, and herbal products.
Seek emergency medical attention if an overdose is suspected.
Symptoms of a diphenhydramine and phenylephrine overdose may include dryness of the mouth, large pupils, flushing, nausea, vomiting, hyperactivity, or hallucinations.
