Fentanyl has a risk for abuse and addiction, which can lead to overdose and death. Fentanyl may also cause severe, possibly fatal, breathing problems. Do not use transdermal patches unless you have been regularly using moderate to large amounts of opioid pain medication. Otherwise, it may cause overdose (even death). To lower your risk, your doctor should have you use the smallest dose of fentanyl that works, and use it for the shortest possible time. See also How to Use section for more information about addiction.

Ask your doctor or pharmacist if you should have naloxone available to treat opioid overdose. Teach your family or household members about the signs of an opioid overdose and how to treat it.

The risk for severe breathing problems is higher when you start this medication and after a dose increase, or if you use the wrong dose/strength. Using this medication with alcohol or other drugs that can cause drowsiness or breathing problems may cause very serious side effects, including death. Be sure you know how to use fentanyl and what other drugs you should avoid using 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.

Do not use this medication to relieve mild, short-term, or sudden pain (such as due to headache/migraine, dental/medical procedures), or pain after surgery (including same-day surgery when you do not need to stay in the hospital overnight). This medication is not for occasional ("as needed") use.

Since they are not used the same way, different forms of fentanyl (including lozenges, buccal tablets, patches) do not have the same effects at equal strengths and should not be substituted for each other. Tell your doctor or pharmacist of all medications that you use, especially of drugs that can affect how fentanyl works. Do not start, stop, or change the dosage of any medicines you are using without your doctor's approval.

Carefully follow the manufacturer's instructions for using fentanyl transdermal patches. The patches are for use on the skin only. Raising your skin/body temperature, using cut or damaged fentanyl patches, or using the patch improperly (such as by chewing it) may cause fatal overdose. Avoid increasing your skin temperature at/near the application site by using products such as heating pads, electric blankets, hot tubs, heat lamps, or tanning lamps. Avoid taking hot baths and sunbathing. However, you may bathe, shower, or swim while wearing the patch as long as you avoid hot water.

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, use 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.

Keep this medicine in a safe place to prevent theft, misuse, or abuse. This medication is not recommended for use by children younger than 2 years. Some manufacturers recommend that this product should not be used by children younger than 18 years. If someone accidentally swallows this drug, get medical help right away.