Guaifenesin / Hydrocodone Side Effects

Medically reviewed by Drugs.com. Last updated on Feb 13, 2025.

Applies to guaifenesin / hydrocodone: oral solution.

Precautions

It is very important that your doctor check your progress while you are using this medicine. This will allow your doctor to see if the medicine is working properly and to decide if you should continue to take it. If your symptoms do not improve or if they get worse, call your doctor.

It is against the law and dangerous for anyone else to use your medicine. Keep your unused oral liquid or tablets in a safe and secure place. People who are addicted to drugs might want to steal this medicine.

Do not use this medicine if you are using or have used an MAO inhibitor (MAOI) such as Eldepryl®, Marplan®, Nardil®, or Parnate® within the past 14 days.

This medicine may be habit-forming. If you feel that the medicine is not working as well, do not use more than your prescribed dose. Call your doctor for instructions.

If you think you or someone else may have taken an overdose of this medicine, get emergency help at once. Signs of an overdose include dark urine, difficult or troubled breathing, irregular, fast or slow, or shallow breathing, nausea or vomiting, pain in the upper stomach, pale or blue lips, fingernails, or skin, pinpoint pupils of the eyes, or yellow eyes or skin.

This medicine may make you dizzy or drowsy. Do not drive or do anything else that could be dangerous until you know how this medicine affects you.

This medicine will add to the effects of alcohol and other CNS depressants (medicines that can make you drowsy or less alert). Some examples of CNS depressants are antihistamines or medicine for allergies or colds, sedatives, tranquilizers, or sleeping medicine, other prescription pain medicine or narcotics, medicine for seizures or barbiturates, muscle relaxants, or anesthetics, including some dental anesthetics. Check with your doctor before taking any of these medicines while you are using this medicine.

Using this medication can cause severe constipation. To prevent this, your doctor may direct you to take laxatives, drink a lot of fluids, or increase the amount of fiber in your diet. Be sure to follow the directions carefully, because continuing constipation can lead to more serious problems.

Dizziness, lightheadedness, or fainting may occur when you get up suddenly from a lying or sitting position. Getting up slowly may help lessen this problem. Also, lying down for a while may relieve the dizziness or lightheadedness.

Using this medicine while you are pregnant may cause serious unwanted effects, including neonatal opioid withdrawal syndrome in your newborn baby. Tell your doctor right away if you think you are pregnant or if you plan to become pregnant while using this medicine.

This medicine may cause adrenal insufficiency. Check with your doctor right away if you have darkening of the skin, diarrhea, dizziness, fainting, loss of appetite, mental depression, nausea, skin rash, unusual tiredness or weakness, or vomiting.

If you have been using this medicine regularly for several weeks or longer, do not suddenly stop using it without first checking with your doctor. Your doctor may want you to gradually reduce the amount you are using before stopping it completely. This may help reduce the possibility of withdrawal symptoms, such as abdominal or stomach cramps, anxiety, fever, nausea, runny nose, sweating, tremors, or trouble sleeping.

Check with your doctor right away if you have anxiety, restlessness, a fast heartbeat, fever, sweating, muscle spasms, twitching, nausea, vomiting, diarrhea, or see or hear things that are not there. These may be symptoms of a serious condition called serotonin syndrome. Your risk may be higher if you also take certain other medicines that affect serotonin levels in your body.

Using too much of this medicine may cause infertility (unable to have children). Talk with your doctor before using the tablet if you plan to have children.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

Other side effects

Some side effects of guaifenesin / hydrocodone may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Serious side effects

Along with its needed effects, guaifenesin / hydrocodone may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking guaifenesin / hydrocodone:

For healthcare professionals

Applies to guaifenesin / hydrocodone: oral capsule, oral liquid, oral syrup, oral tablet, oral tablet extended release.

General adverse events

The most commonly reported adverse effects have included headache, dizziness, sedation, nausea, diarrhea, decreased blood pressure, and flushing.^[Ref]

Nervous system

• Frequency not reported: Sedation (somnolence), headache, dizziness, decreased mental alertness with impaired mental and/or physical abilities

Hydrocodone:

Increased intracranial pressure^[Ref]

Respiratory

• Frequency not reported: Dose-related respiratory depression including fatal respiratory depression^[Ref]

Gastrointestinal

• Frequency not reported: Nausea, diarrhea

Hydrocodone:

• Frequency not reported: Paralytic ileus^[Ref]

Dermatologic

• Frequency not reported: Hot flush^[Ref]

Cardiovascular

• Frequency not reported: Decreased blood pressure^[Ref]

Psychiatric

• Frequency not reported: Mental clouding, anxiety, fear, dysphoria, drug dependence, mood changes, sleeplessness

See also:

Further information

Guaifenesin/hydrocodone side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Note: Medication side effects may be underreported. If you are experiencing side effects that are not listed, submit a report to the FDA by following this guide.

Medical Disclaimer