[Edaily Reporter NA EUN-KYUNG ] Have you ever taken a headache medication before bed because of a headache, only to find that while the pain subsided, you became wide awake instead? It’s easy to assume that taking the medicine will help you relax and fall asleep, but some pain relievers contain caffeine, which can interfere with sleep.

Caffeine isn’t a component found only in coffee or energy drinks. It’s also included in some over-the-counter medications for headaches or cold symptoms under the name “caffeine anhydrous.” This is caffeine in a dehydrated form, and once ingested, it stimulates the central nervous system just like the caffeine found in coffee.

Representative products include “Geborin Tablets” from SamjinPharmaceutical(005500)and “Penjal Q Tablets” from CHONGKUNDANG(185750). Geborin Tablets contain 300 mg of acetaminophen, 150 mg of isopropylantipyrine, and 50 mg of anhydrous caffeine. Penzal Q Tablets contain 300 mg of acetaminophen, 200 mg of ethenzamide, and 50 mg of anhydrous caffeine. This means that both products contain 50 mg of caffeine per tablet.

The inclusion of caffeine in pain relievers is not merely to combat drowsiness. When used in combination with acetaminophen or ibuprofen, caffeine can enhance the analgesic effect for certain types of acute pain. However, people who are sensitive to caffeine may experience difficulty falling asleep, heart palpitations, anxiety, or hand tremors even after consuming small amounts.

The half-life of caffeine in the body averages 2 to 6 hours in healthy adults, but it can be as long as 12 hours depending on the individual. This means that a significant amount of caffeine ingested in medication in the evening may still be present by the time you go to bed. If you usually have trouble sleeping after drinking coffee, you should be especially careful when taking caffeine-containing pain relievers right before bedtime.

Caffeine is also found in cold remedies. “Pancol ES Oral Solution” by DongwhaPharm(000020)and “Panpirin Q Solution” by #Dong-A Pharmaceutical each contain 30 mg of anhydrous caffeine per bottle. Both products contain 300 mg of acetaminophen, which reduces fever and pain, along with various other ingredients that treat runny nose, cough, and phlegm.

Pancol and Panpirin also contain chlorpheniramine, a first-generation antihistamine that can cause drowsiness. This means that a single product contains both an ingredient that can induce drowsiness and caffeine, which can cause alertness. Since reactions vary from person to person, you may feel drowsy after taking these medications, or conversely, you may have trouble falling asleep. You should not take cold medicine before driving, even if you assume it will make you drowsy, nor should you take it specifically to help you fall asleep.

Ingredients used to relieve nasal congestion or coughing can also affect sleep. DL-methylephedrine, found in Pancol and Panpirin, and pseudoephedrine, found in Actipid tablets, stimulate the sympathetic nervous system and can cause heart palpitations or insomnia in some people. Therefore, even if a product does not contain caffeine, you may have trouble falling asleep after taking cold or rhinitis medications that contain decongestants.

However, this does not mean you should never take pain relievers or cold medicines containing caffeine at night. If pain or cold symptoms are interfering with your sleep, taking medication to alleviate those symptoms may actually help you sleep better. However, if you are sensitive to caffeine or suffer from insomnia, it is best to check the active ingredients on the product packaging or in the package insert and consult a pharmacist to choose a caffeine-free product.

For example, Tylenol 500 mg tablets are a single-ingredient medication containing only acetaminophen. Since caffeine-containing combination medications are not strictly necessary for relieving headaches or fever, you may consider such single-ingredient products at night, depending on your symptoms and health condition. However, acetaminophen is not suitable for everyone. People with liver disease or those who have consumed alcohol may face an increased risk of side effects, such as liver damage, and should consult a healthcare professional before taking it.

Caffeine intake should be calculated by combining the caffeine from coffee and energy drinks. If you drink several cups of coffee during the day and then take medications such as Geborin, Penzal Q, Pancol, or Panpirin, your caffeine intake may increase without you realizing it. While the U.S. Food and Drug Administration (FDA) generally considers up to 400 mg per day to be a level not associated with adverse effects for healthy adults, sensitivity to caffeine and metabolic rates vary from person to person.

When taking combination medications, the overlap of acetaminophen can be a bigger problem than that of caffeine. Geborin, Penzal Q, Pancol, and Panpirin all contain acetaminophen. If you take an acetaminophen-based pain reliever after taking cold medicine because your headache or fever hasn’t subsided, you may end up taking the same ingredient twice. Since exceeding the maximum daily dose of 4,000 mg of acetaminophen can increase the risk of liver damage, it should not be taken in combination with other products.

When choosing a medication, don’t just look at the intended use—such as “headache medicine” or “cold medicine”—printed on the front of the package; be sure to check the active ingredients and dosages listed on the back. Especially late at night, it’s a good idea to check whether the product contains caffeine or decongestants and to ensure there is no overlap between acetaminophen and other medications you’ve already taken. If your pain has subsided but you still can’t fall asleep, it may be due not only to an underlying condition but also to the caffeine in the medication.