Nausea, vomiting, constipation, lightheadedness, dizziness, drowsiness, increased sweating, or dry mouth may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.

To prevent constipation, maintain a diet adequate in fiber, drink plenty of water, and exercise. Consult your pharmacist for help in selecting a laxative (such as a stimulant type with stool softener).

Remember that your doctor has prescribed this medication because he or she 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 immediately if any of these unlikely but serious side effects occur: fainting, mental/mood changes (such as agitation, hallucinations, confusion), difficulty urinating, vision changes, fast heartbeat.

Tell your doctor immediately if any of these rare but very serious side effects occur: slow/shallow breathing, change in the amount of urine, signs of infection (such as fever, persistent sore throat), seizures, easy bruising/bleeding.

A very serious allergic reaction to this drug is rare. However, seek immediate medical attention if you notice any of the following symptoms of a serious allergic reaction: 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.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Read the Talacen (pentazocine and acetaminophen) Side Effects Center for a complete guide to possible side effects »

PRECAUTIONS: See also Warning section.

Before taking this product, tell your doctor or pharmacist if you are allergic to pentazocine or acetaminophen; or if you have any other allergies. This product may contain inactive ingredients (such as sulfites), which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

This medication should not be used if you have certain medical conditions. Before using this medicine, consult your doctor or pharmacist if you have: certain bowel diseases (paralytic ileus, infectious diarrhea).

Before using this medication, tell your doctor or pharmacist your medical history, especially of: kidney disease, liver disease, lung disease (such as asthma, chronic obstructive pulmonary disease-COPD), a certain spinal problem (kyphoscoliosis), breathing problems (such as slow/shallow breathing, sleep apnea), certain heart problems (irregular heartbeat, recent heart attack), personal or family history of regular use/abuse of drugs/alcohol, brain disorders (such as seizures, head injury, tumor, increased intracranial pressure), underactive thyroid (hypothyroidism), difficulty urinating (for example, due to enlarged prostate or narrowed urethra), disease of the pancreas (such as pancreatitis), mental/mood disorders (such as toxic psychosis), gallbladder disease, adrenal gland problem (such as Addison's disease), intestinal disorders (such as colitis, blockage), certain blood disorders (porphyrias).

This drug may make you dizzy or drowsy. Do not drive, use machinery, or do any activity that requires alertness until you are sure you can perform such activities safely. Avoid alcoholic beverages.

Before having surgery, tell your doctor or dentist that you are using this medication.

To lower your risk of dizziness and lightheadedness, get up slowly when rising from a sitting or lying position.

Older adults may be more sensitive to the effects of this drug, especially slow/shallow breathing and drowsiness.

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 if you plan to become pregnant. During pregnancy, this medication should be used only when clearly needed. 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. Tell the doctor right away if you notice any symptoms in your newborn baby such as slow/shallow breathing, irritability, abnormal/persistent crying, vomiting, or diarrhea.

It is unknown if pentazocine passes into breast milk. Acetaminophen passes into breast milk. Discuss the risks and benefits with your doctor before breast-feeding.