The Effects of Tylenol PM for Sleep

Tylenol PM is an over-the-counter medication indicated for the treatment of pain and mild insomnia. Tylenol PM is a combination of the drugs diphenhydramine and acetaminophen. Diphenhydramine is an anti-histamine used to promote sleep and reduce inflammation, while acetaminophen reduces fever and pain. Taken together, Tylenol PM can help people with the common cold, flu or fever get to sleep and relieve pain. Diphenhydramine and acetaminophen have been studied extensively in clinical trials and post-marketing research. Tylenol PM has proven generally safe and effective, but also can cause several side effects.

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Sleep Aid and Fever Reduction

One of the desired effects of Tylenol PM is to help people fall asleep easier. Patients may have trouble falling asleep due to the common cold, fever, flu or another condition. Diphenhydramine is an effective non-habit-forming medication for inducing sleep. Anti-histamines like diphenhydramine work by slowing down the activity in the central nervous system. Dr. Jerome Seigel at the University of California-Los Angeles, states that histamine, a neurotransmitter and hormone, is an essential key to wakefulness. Anti-histamines also help to lower body temperature and inflammation, which can help to relieve fever. Histamines are released in the nasal passages when someone has a cold, and this is partly responsible for sneezing. According to, Tylenol PM can also help reduce sneezing, runny nose and watery eyes.

Pain Relief

Tylenol PM also relieves minor aches and pains. Diphenhydramine can reduce the pain caused by inflammation, while acetaminophen reduces pain by activating receptors in the body, called cannabinoids. In the February 2006 issue of the "European Journal of Pharmacology," Dr. Alessandra Ottani and associates found that acetaminophen, also known as paracetamol, blocks pain reception at two specific cannabinoid receptors in the body. According to Family, the acetaminophen in Tylenol PM is a good choice for relieving headaches and other common aches and pains. It can be used on a long-term basis for people with arthritis and other conditions that result in chronic pain.

Side Effects

Tylenol PM can also result in several side effects. According to, one of the most common side effects is sedation. Diphenhydramine is a central nervous system depressant, so patients may feel a slight hangover effect the next morning after taking Tylenol PM. Other nervous system effects may include dizziness, confusion, memory impairment, rigidity and impaired motor skills. Patients taking Tylenol PM should not drive or use heavy machinery. Another side effect of frequent high doses of acetaminophen is liver damage. If patients are taking more than the recommended dose, they should consult their physician about possible liver damage.