This combination medication is used to temporarily treat cough, chest congestion, and stuffy nose symptoms caused by the common cold, flu, or other breathing illnesses (such as sinusitis, bronchitis). Guaifenesin is an expectorant that helps thin and loosen mucus in the lungs, making it easier to cough up the mucus. The decongestant helps relieve stuffy nose symptoms. This product also contains an opioid cough suppressant (antitussive) that affects a certain part of the brain, reducing the urge to cough.This medication is not usually used for ongoing coughs from smoking, asthma, other long-term breathing problems (such as emphysema), or coughs with a lot of mucus unless directed by your doctor.Opioid cough suppressants should not be used by children younger than 18 years. Children are at higher risk for serious (even fatal) side effects, especially breathing problems. Talk with the doctor about the risks and benefits of this medication.Cough-and-cold products do not cure colds. Cough due to a common cold often does not need to be treated with medicine. Ask your doctor or pharmacist about other ways to relieve cough and cold symptoms, such as drinking enough fluids, using a humidifier, or saline nose drops/spray.
How to use Phenhist Syrup
Take this medication by mouth with or without food with a full glass of water (8 ounces or 240 milliliters) as directed by your doctor. This medication can be taken with food if stomach upset occurs. Drink plenty of fluids when you use this medication unless otherwise directed by your doctor. The fluid will help loosen the mucus in your lungs.
If you are using the liquid form, use a medication-measuring device or spoon to carefully measure the prescribed dose. Do not use a household spoon because you may not get the correct dose. If your liquid form is a suspension, shake the bottle well before each dose.
The dosage is based on your medical condition and response to treatment.
Do not increase your dose or use this product more often or for longer than prescribed. Your condition will not improve any faster, and your risk of side effects will increase.
If you suddenly stop using this medication, you may have withdrawal symptoms (such as restlessness, watering eyes, runny nose, nausea, sweating, muscle aches). To help prevent withdrawal, your doctor may lower your dose slowly. Withdrawal is more likely if you have used this medication regularly for a long time (more than a few weeks) or in high doses. Tell your doctor or pharmacist right away if you have withdrawal.
Though it helps many people, this product has a risk for abuse and may sometimes cause addiction. This risk may be higher if you have a substance use disorder (such as overuse of or addiction to drugs/alcohol). Take this product exactly as prescribed to lower the risk of addiction. Ask your doctor or pharmacist for more details.
When used for an extended time, this medication may not work as well and may require different dosing. Talk with your doctor if this medication stops working well.
Tell your doctor if your cough does not get better in 5 days. Also, tell your doctor if your condition gets worse, or if you have a headache that doesn't go away, fever, or rash. These may be symptoms of a serious medical problem and should be checked by a doctor.
See also Warning section.
Dizziness, drowsiness, headache, upset stomach, nausea, constipation, nervousness, or trouble sleeping may occur. If any of these effects last or get worse, contact your doctor or pharmacist promptly.
To reduce the risk of dizziness and lightheadedness, get up slowly when rising from a sitting or lying position.
Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.
Tell your doctor right away if you have any serious side effects, including: interrupted breathing during sleep (sleep apnea), mental/mood changes (such as hallucinations), shaking, trouble urinating, weakness, fast/irregular heartbeat.
Get medical help right away if you have any very serious side effects, including: seizure.
This product may cause serious mental/mood changes and very serious (rarely fatal) breathing problems. This product may contain codeine or dihydrocodeine. Codeine and dihydrocodeine are changed into strong opioid drugs (morphine or dihydromorphine) in your body. In some people this happens faster and more completely than usual, which increases the risk of very serious side effects. Get medical help right away if you notice any of the following: slow/shallow breathing, severe drowsiness/difficulty waking up, confusion.
A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.
This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.
In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.
In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.
This medication has a risk for abuse and addiction, which can lead to overdose and death. This medication may also cause severe, possibly fatal, breathing problems. To lower your risk, your doctor should have you take the smallest dose that works, and take it for the shortest possible time. See also How to Use section for more information about addiction.
The risk for severe breathing problems is higher when you start this medication, or if you take the wrong dose or take more of this medication than prescribed. Taking this medication with alcohol or other drugs that can cause drowsiness or breathing problems may cause very serious side effects, including death. Also, other medications can affect the removal of this product from your body, which may affect how it works. Be sure you know how to take this product and what other drugs you should avoid taking with it. See also Drug Interactions section. Get medical help right away if any of these very serious side effects occur: slow/shallow breathing, unusual lightheadedness, severe drowsiness/dizziness, difficulty waking up.
Keep this medicine in a safe place to prevent theft, misuse, or abuse. If someone accidentally swallows this drug, get medical help right away.
Before using this medication, women of childbearing age should talk with their doctor(s) about the risks and benefits. Tell your doctor if you are pregnant or think you may be pregnant. During pregnancy, this medication is not recommended. It may slightly increase the risk of birth defects if used during the first two months of pregnancy. Also, using it for a long time or in high doses near the expected delivery date may harm the unborn baby. To lessen the risk, take the smallest effective dose for the shortest possible time. Babies born to mothers who use this drug for a long time may develop severe (possibly fatal) withdrawal symptoms. Tell the doctor right away if you notice any symptoms in your newborn baby such as crying that doesn't stop, slow/shallow breathing, irritability, shaking, vomiting, diarrhea, poor feeding, or difficulty gaining weight.
Before taking this medication, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.
Before using this medication, tell your doctor or pharmacist your medical history, especially of: abdominal problems (such as chronic constipation, ileus, gallbladder disease, pancreatitis), adrenal gland problem (such as Addison's disease), blood vessel problems (such as Raynaud's disease, low blood flow to the brain/legs/hands), certain brain disorders (such as head injury, tumor, increased pressure in the brain, seizures), breathing problems (such as asthma, emphysema, sleep apnea), diabetes, glaucoma, heart problems, high blood pressure, kidney problems, liver disease, mental/mood problems (such as depression, psychosis), thyroid problems (such as hyperthyroidism, hypothyroidism), trouble urinating (such as due to enlarged prostate), personal or family history of a substance use disorder (such as overuse of or addiction to drugs/alcohol), obesity.
This drug may make you dizzy or drowsy. Alcohol or marijuana (cannabis) can make you more dizzy or drowsy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Avoid alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).
This medicine may contain aspartame. If you have phenylketonuria (PKU) or any other condition that requires you to restrict your intake of aspartame (or phenylalanine), consult your doctor or pharmacist regarding the safe use of this medicine.
Older adults may be more sensitive to the side effects of this drug, especially confusion, dizziness, drowsiness, slow/shallow breathing, fast/irregular heartbeat, problems urinating, or trouble sleeping.
Tell your doctor if you are pregnant or think you may be pregnant. During pregnancy, this product is not recommended. It may harm an unborn baby. Talk to your doctor about the risks and benefits of this medication. See also Warning section.
This product may pass into breast milk and may have undesirable effects on a nursing infant (such as unusual sleepiness, difficulty feeding, trouble breathing, or unusual limpness). Consult your doctor before breast-feeding.
See also Warning section.
Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.
Taking MAO inhibitors with this medication may cause a serious (possibly fatal) drug interaction. Avoid taking MAO inhibitors (isocarboxazid, linezolid, metaxalone, methylene blue, moclobemide, phenelzine, procarbazine, rasagiline, safinamide, selegiline, tranylcypromine) during treatment with this medication. Most MAO inhibitors should also not be taken for two weeks before treatment with this medication. Ask your doctor when to start or stop taking this medication.
The risk of serious side effects (such as slow/shallow breathing, severe drowsiness/dizziness) may be increased if this medication is taken with other products that may also cause drowsiness or breathing problems. Tell your doctor or pharmacist if you are taking other products such as other opioid pain or cough relievers (such as codeine, hydrocodone), alcohol, marijuana (cannabis), drugs for sleep or anxiety (such as alprazolam, lorazepam, zolpidem), muscle relaxants (such as carisoprodol, cyclobenzaprine), or antihistamines (such as cetirizine, diphenhydramine).
Guaifenesin and decongestants are available in both prescription and nonprescription products. Check the labels on all your medications carefully to make sure you are not taking more than one product containing these ingredients.
Check the labels on all your medicines (such as allergy or cough-and-cold products, diet aids) because they may contain ingredients that cause drowsiness or affect your heart rate/blood pressure. Ask your pharmacist about using those products safely.
Other medications can affect the removal of this product from your body, which may affect how this product works. Examples include azole antifungals (such as ketoconazole), bupropion, fluoxetine, macrolide antibiotics (such as erythromycin), paroxetine, quinidine, rifamycins (such as rifabutin, rifampin), ritonavir, certain drugs used to treat seizures (such as carbamazepine, phenytoin), among others.
This medication may interfere with certain lab tests (such as 5-HIAA levels, VMA levels, amylase/lipase levels), possibly causing false test results. Make sure lab personnel and all your doctors know you use this drug.
If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center. Symptoms of overdose may include: confusion, cold/clammy skin, fast/irregular heartbeat, slow/shallow breathing, seizures, coma.
Do not share this medication with others. Sharing it is against the law.
If you are prescribed this medication on a regular schedule and miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.
Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications away from children and pets.
Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.
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CONDITIONS OF USE: The information in this database is intended to supplement, not substitute for, the expertise and judgment of healthcare professionals. The information is not intended to cover all possible uses, directions, precautions, drug interactions or adverse effects, nor should it be construed to indicate that use of a particular drug is safe, appropriate or effective for you or anyone else. A healthcare professional should be consulted before taking any drug, changing any diet or commencing or discontinuing any course of treatment.