Acetaminophen Risks, Warnings, and Complications

Precautions Before Starting Acetaminophen

Tell your doctor if you have ever developed a skin rash after taking acetaminophen. Also, tell your doctor if you have an allergy to any of the active or inactive ingredients in acetaminophen tablets or an allergy to any other drugs. Your pharmacy can give you a list of ingredients.

Give your doctor a complete medical history. Acetaminophen may not be right for people with certain medical conditions such as liver disease or alcoholism.

Give your doctor and pharmacist a complete list of your medications, including prescription drugs, over-the-counter medicines, vitamins, supplements, and herbal products. This can help avoid possible drug interactions.

Do not take over-the-counter acetaminophen if you drink three or more alcoholic beverages per day. Talk to your doctor or pharmacist about the safety of drinking alcohol while taking acetaminophen.

Tell your doctor if you are pregnant, could be pregnant, are planning a pregnancy, or are breastfeeding. 

People with a condition called phenylketonuria should talk to their doctor about which acetaminophen products are safe for them to use. In this condition, high serum levels of an amino acid called phenylalanine can cause serious problems. Some brands of nonprescription (OTC) acetaminophen products like chewable tablets may contain aspartame which gets broken down into phenylalanine. Regular acetaminophen tablets and liquid medicine don't contain phenylalanine. If you have phenylketonuria, talk to your healthcare provider about what acetaminophen products are safe for you.

Precautions During Use of Acetaminophen

Call your doctor if your pain lasts more than 10 days, your fever gets worse or lasts more than 3 days, or you develop other new symptoms like skin redness after taking acetaminophen. 

Do not take a chronic high dose of acetaminophen regularly without talking to a healthcare provider. If you have severe pain, consult a doctor for appropriate pain management options. 

Acetaminophen is present along with other medications in many combination products, some of which are available by prescription and some without a prescription. If your doctor has prescribed acetaminophen, do not take other non-prescription pain medications that also contain acetaminophen. Check the label of all over-the-counter medicines, especially those used to treat cough or cold symptoms, as they may contain acetaminophen. Avoid using two or more products at the same time because they may contain the same active ingredient and could lead to an acetaminophen overdose. This is especially true for children younger than 2 years of age. 

When giving non-prescription acetaminophen products to children, read the package label to ensure you are using an acetaminophen product that is suitable for children. 

Tell your doctor if you become pregnant while taking acetaminophen.

Tell all your doctors you are on acetaminophen before any surgery, including dental procedures.

Acetaminophen Drug Interactions

Certain other drugs can affect how acetaminophen works. Possible interactions between acetaminophen and other medicines can increase the risk of severe adverse effects. Your doctor may change the dose of your medications or monitor you carefully for side effects if there are known interactions between acetaminophen and your other medicines. The following medications can have possible interactions with acetaminophen:

• Blood thinners (anticoagulants) like warfarin (Coumadin)
• Medications used to relieve pain, fever, coughs, and colds
• Certain medications used to treat seizures, such as phenobarbital, phenytoin (Dilantin), and carbamazepine (Tegretol)
• Tuberculosis medications like isoniazid (INH)
• Phenothiazines (medications used to treat mental illness and nausea)

The above list may not include all the possible interactions of acetaminophen. Give your doctor or pharmacist a complete list of your medications, including prescription drugs, over-the-counter medicines, dietary supplements, and herbal remedies. Also, tell your healthcare professional if you smoke, drink alcohol, or use recreational drugs because some of these substances can cause serious health complications when used with prescription and over-the-counter medicines.