Midol & Caffeine

Caffeine is a psycho-stimulant occurring naturally in more than 60 plants, and it is the most widely consumed stimulant drug in the world. Caffeine affects the central nervous system to produce feelings of alertness and increased energy and also plays a role in modifying pain. Caffeine is commonly added to the PMS relief drug Midol, as well as other acetaminophen-based pain relievers to enhance their effectiveness. Although caffeine in Midol is used to treat a range of PMS symptoms, caffeine may also worsen PMS.

Caffeine and Physiology

In your brain, a neurotransmitter known as adenosine is responsible for regulating your sleep-wake cycles. Caffeine's effects of making you feel more alert and awake owe to the way it in which it blocks adenosine receptors, and consequently speeds up neural activity. When caffeine binds to the adenosine receptor sites, it also causes the constriction of blood vessels, which contributes to pain relief.

Caffeine and Midol

Midol is an over-the-counter pain relief drug marketed specifically for the symptoms associated with PMS, or premenstrual syndrome. According to the Midol company, which is a subsidiary of the pharmaceuticals firm Bayer, Midol works not only to relieve pain but also helps to treat PMS-associated symptoms of fatigue and bloating. Midol Complete contains 60 mg of caffeine per capsule, which according to the FDA is an amount equivalent to one cup of coffee. Bayer maintains that caffeine is added to Midol to help combat fatigue and to act as a diuretic to help relieve bloating.

Caffeine and Pain

In a review article published in August 2008 on the relationship between caffeine and headaches, Dr. R. E. Shapiro notes that although it is not clear why caffeine offers pain relief, it likely increases the rate at which pain relievers are absorbed into the body. Consuming caffeine in beverage form might offer possible relief for pain; however, as of 2011, there is inconclusive evidence on the pain relieving effects of caffeinated beverages. As most Americans consume caffeine regularly, the analgesic effects of caffeine are reduced because of high tolerance levels. High tolerance levels may also limit the efficacy of Midol and other caffeine-added pain relievers.

Caffeine and PMS

Although caffeine can help reduce feelings of pain and is added to Midol to bring PMS relief, other research suggests that caffeine worsens PMS symptoms. In a November 1995 article titled "A Clinician's Guide to the Premenstrual Syndrome," gynecologists from the University of Pennsylvania Medical Center advise that women experiencing PMS should avoid caffeine. According to the Ash Center for Comprehensive Medicine, caffeine consumption aggravates PMS symptoms because of the complex relationship between caffeine, adenosine and hormone regulation.