Signs and symptoms of medication overuse headaches may differ according to the type of original headache being treated and the medication used. Medication overuse headaches tend to:

• Occur every day or nearly every day, often waking you in the early morning

• Improve with pain relief medication but then return as your medication wears off

Other signs and symptoms may include:

• Nausea

• Restlessness

• Difficulty concentrating

• Memory problems

• Irritability

Doctors don't yet know exactly why medication overuse leads to rebound headaches. The risk of developing medication overuse headaches varies depending on the medication, but any acute headache medication has the potential to lead to medication overuse headaches, including:

• Simple pain relievers. Common pain relievers such as aspirin and acetaminophen (Tylenol, others) may contribute to medication overuse headaches — especially if you exceed the recommended daily dosages. Pain relievers such as ibuprofen (Advil, Motrin IB, others) and naproxen sodium (Aleve) have a low risk of contributing to medication overuse headaches.

• Combination pain relievers. Over-the-counter (OTC) pain relievers that combine caffeine, aspirin and acetaminophen (Excedrin, others) are common culprits.

This group also includes prescription medications such as Fiorinal, which contains the sedative butalbital. Butalbital-containing compounds have an especially high risk of causing medication overuse headaches, so it's best not to take them to treat headaches.

• Migraine medications. Various migraine medications have been linked with medication overuse headaches, including triptans (Imitrex, Zomig, others) and certain ergots — such as ergotamine (Ergomar, others). These medications have a moderate risk of causing medication overuse headaches. The ergot dihydroergotamine (D.H.E. 45) appears to have a lower potential for leading to this problem.

• Opiates. Painkillers derived from opium or from synthetic opium compounds include combinations of codeine and acetaminophen (Tylenol with Codeine No. 3 and No. 4, others). These medications have a high risk of causing medication overuse headaches.

Daily doses of caffeine — from coffee, soda, and pain relievers and other products containing this mild stimulant — may fuel medication overuse headaches, as well. Read product labels to make sure you're not wiring your system with more caffeine than you realize.

Risk factors for developing medication overuse headaches include:

• History of chronic headaches. A history of chronic headaches, especially migraines, puts you at risk.

• Frequent use of headache medications. Your risk increases if you use combination analgesics, ergotamine or triptans 10 or more days a month or simple analgesics more than 15 days a month — especially if this regular use continues for three or more months.