Generic Name: guaifenesin and phenylephrine (gwye FEN e sin and FEN il EFF rin)
Brand Names: Amitex LA, Crantex, Deconex, Deconsal II, Despec, Duraphen II, Duratuss PE, Genexa LA, Gentex LA, Guaifed Caps, Liquibid-D, Lusonex, Nasex-G, Nescon-PD, Phenavent, Prolex D, Rescon-GG, Sina-12X, Sinupan, SINUvent PE, Wellbid-D, Xedec
What is Phenavent LA (guaifenesin and phenylephrine)?
Guaifenesin is an expectorant. It helps loosen congestion in your chest and throat, making it easier to cough out through your mouth.
Phenylephrine is a decongestant that shrinks blood vessels in the nasal passages. Dilated blood vessels can cause nasal congestion (stuffy nose).
The combination of guaifenesin and phenylephrine is used to treat stuffy nose and sinus congestion, and to reduce chest congestion caused by the common cold or flu.
Guaifenesin and phenylephrine may also be used for other purposes not listed in this medication guide.
What is the most important information I should know about Phenavent LA (guaifenesin and phenylephrine)?Always ask a doctor before giving a cough or cold medicine to a child. Death can occur from the misuse of cough and cold medicines in very young children. Do not use any other over-the-counter cough, cold, allergy, or sleep medication without first asking your doctor or pharmacist. If you take certain products together you may accidentally take too much of one or more types of medicine. Read the label of any other medicine you are using to see if it contains an antihistamine, decongestant, or cough suppressant.
What should I discuss with my healthcare provider before taking Phenavent LA (guaifenesin and phenylephrine)?Do not use this medication if you are allergic to guaifenesin or phenylephrine, or to other decongestants, diet pills, stimulants, or ADHD medications. Do not use a cough or cold medicine if you have used an MAO inhibitor such as isocarboxazid (Marplan), phenelzine (Nardil), rasagiline (Azilect), selegiline (Eldepryl, Emsam), or tranylcypromine (Parnate) within the past 14 days. Serious, life-threatening side effects can occur if you take cough or cold medicine before the MAO inhibitor has cleared from your body.
Before taking this medication, tell your doctor if you have
heart disease or high blood pressure;
a thyroid disorder;
overactive thyroid; or
enlarged prostate or problems with urination.
If you have any of these conditions, you may not be able to use this medication, or you may need a dosage adjustment or special tests during treatment.FDA pregnancy category C. This medication may be harmful to an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant during treatment. This medication passes into breast milk and could harm a nursing baby. Do not use this medication without telling your doctor if you are breast-feeding a baby. This medication may be harmful to an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant during treatment.
Artificially-sweetened liquid forms of cold medicine may contain phenylalanine. This would be important to know if you have phenylketonuria (PKU). Check the ingredients and warnings on the medication label if you are concerned about phenylalanine.
How should I take Phenavent LA (guaifenesin and phenylephrine)?
Use this medication exactly as directed on the label, or as it has been prescribed by your doctor. Do not use the medication in larger amounts, or use it for longer than recommended. Cold medicine is usually taken only for a short time until your symptoms clear up.Always ask a doctor before giving cough or cold medicine to a child. Death can occur from the misuse of cough or cold medicine in very young children.
Measure the liquid form of this medicine with a special dose-measuring spoon or cup, not a regular table spoon. If you do not have a dose-measuring device, ask your pharmacist for one.Do not crush, chew, break, or open a controlled-release, delayed-release, or extended-release tablet or capsule. Swallow the pill whole. It is specially made to release medicine slowly in the body. Breaking or opening the pill would cause too much of the drug to be released at one time. Take guaifenesin and phenylephrine with food if it upsets your stomach. Talk with your doctor if your symptoms do not improve after 7 days of treatment, or if you have a fever with a headache, cough, or skin rash. Drink extra fluids to help loosen the congestion and lubricate your throat while you are taking this medication.
What happens if I miss a dose?
Since cough or cold medicine is usually taken only as needed, you may not be on a dosing schedule. If you are taking the medication regularly, take the missed dose as soon as you remember. If it is almost time for your next dose, skip the missed dose and take the medicine at your next regularly scheduled time. Do not take extra medicine to make up the missed dose.
What happens if I overdose?Seek emergency medical attention if you think you have used too much of this medicine.
Symptoms of an overdose may include nausea, vomiting, numbness or tingly feeling, dizziness, and feeling restless or nervous.
What should I avoid while taking Phenavent LA (guaifenesin and phenylephrine)?Avoid drinking alcohol while you are taking this medicine. Do not use any other over-the-counter cough, cold, allergy, or sleep medication without first asking your doctor or pharmacist. If you take certain products together you may accidentally take too much of one or more types of medicine. Read the label of any other medicine you are using to see if it contains an antihistamine, decongestant, or cough suppressant.
Avoid taking diet pills, caffeine pills, or other stimulants (such as ADHD medications) without your doctor's advice. Taking a stimulant together with a decongestant can increase your risk of unpleasant side effects.This medication can cause side effects that may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be awake and alert.
Phenavent LA (guaifenesin and phenylephrine) side effectsGet emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat. Stop using this medication and call your doctor at once if you have any of these serious side effects:
fast, pounding, or uneven heartbeat;
severe dizziness, anxiety, restless feeling, or nervousness;
easy bruising or bleeding, unusual weakness, fever, chills, body aches, flu symptoms;
increased blood pressure (severe headache, blurred vision, trouble concentrating, chest pain, numbness, seizure);
nausea, stomach pain, low fever, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes);
Less serious side effects may include:
nausea, vomiting, upset stomach, loss of appetite;
warmth, tingling, or redness under your skin;
feeling excited or restless;
sleep problems (insomnia);
skin rash or itching;
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.
See also: Phenavent LA side effects (in more detail)
What other drugs will affect Phenavent LA (guaifenesin and phenylephrine)?
Before taking this medication, tell your doctor if you use any of the following drugs:
medicines to treat high blood pressure;
a beta-blocker such as atenolol (Tenormin), carteolol (Cartrol), metoprolol (Lopressor, Toprol), nadolol (Corgard), propranolol (Inderal), sotalol (Betapace), timolol (Blocadren), and others; or
antidepressants such as amitriptyline (Elavil), clomipramine (Anafranil), imipramine (Janimine, Tofranil), and others.
This is not a complete list and there may be other drugs that can interact with guaifenesin and phenylephrine. Tell your doctor about all the prescription and over-the-counter medications you use. This includes vitamins, minerals, herbal products, and drugs prescribed by other doctors. Do not start using a new medication without telling your doctor. Keep a list with you of all the medicines you use and show this list to any doctor or other healthcare provider who treats you.
More Phenavent LA resources
Where can I get more information?
- Your pharmacist can provide more information about guaifenesin and phenylephrine.
- Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.
- Disclaimer: Every effort has been made to ensure that the information provided by Cerner Multum, Inc. ('Multum') is accurate, up-to-date, and complete, but no guarantee is made to that effect. Drug information contained herein may be time sensitive. Multum information has been compiled for use by healthcare practitioners and consumers in the United States and therefore Multum does not warrant that uses outside of the United States are appropriate, unless specifically indicated otherwise. Multum's drug information does not endorse drugs, diagnose patients or recommend therapy. Multum's drug information is an informational resource designed to assist licensed healthcare practitioners in caring for their patients and/or to serve consumers viewing this service as a supplement to, and not a substitute for, the expertise, skill, knowledge and judgment of healthcare practitioners. The absence of a warning for a given drug or drug combination in no way should be construed to indicate that the drug or drug combination is safe, effective or appropriate for any given patient. Multum does not assume any responsibility for any aspect of healthcare administered with the aid of information Multum provides. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the drugs you are taking, check with your doctor, nurse or pharmacist.