Name: acetylsalicylic acid; aspirin; 2-acetoxybenzoic acid
CAS Number: 50-78-2
Chemical Formula: C9H8O4
Molar Mass: 180.15742 g
Mass Percent: C 60.001 %; H 4.4758 %; O 35.523 % 


• organic • aromatic • carboxylic acid • ester


• "...aspirin." 1

• "Analgesic; antipyretic; anti-inflammatory." 2

• "Aspirin is an inexpensive, widely used over-the-counter drug, yet it is still an important addition to most immune treatment protocols. Aspirin is a non steroidal anti-inflammatory drug that works at a different level than heparin to stop platelets clumping together and causing a clot. It also assists in widening the blood vessels by relaxing their walls. The result is improved blood flow and circulation around the body, including the uterus and ovaries. A randomized clinical trial carried out at the Harvard Medical School hospital in 2004 has also demonstrated that low dose aspirin triggers the body to generate its own anti-inflammatory compounds to fight inflammation and disease.

As well as increasing ovarian responsiveness, aspirin therapy has been shown to produce better implantation and pregnancy rates in trials. Improved IVF cycle outcomes have also been seen when it is taken during the ovarian stimulation phase.

Aspirin therapy is usually started on the first day of the cycle of conception (the first day of the period) and taken throughout the entire pregnancy. Although aspirin is able to cross the placenta, the does is so small the fetus is unlikely to be affected. Indeed, there is currently no evidence to show that aspirin exposure causes fetal abnormalities. However, it has demonstrated a beneficial effect, by significantly reducing the incidence of stillbirth and preeclampsia.

To protect the stomach from excess acidity, soluble forms of low dose aspirin are dissolved in water before they are taken. Those labeled "enteric coated" can be swallowed whole as they have a special outer layer that acts as a buffer to protect the stomach and prevent the drug from being absorbed being absorbed too quickly. Antacids (indigestion remedies) should not be taken at the same time as aspirin.

In approximately 2.5% of people who take the drug (compared to 1.4% who do not), aspirin therapy carries a risk of bleeding or ulceration of the stomach or intestines. It should therefore be avoided by anyone with stomach ulcers or a known bleeding tendency. The risk if side effects is slightly increased when it is taken in addition to corticosteroids. In rare incidences, aspirin may cause gastrointestinal problems." 3

• "The exclusive use of aspirin is as a medicine. It has three important properties as a drug. It relieves pain, reduces inflammation, and reduces fever. In addition to its effectiveness in treating these medical symptoms, it is inexpensive and available in a variety of forms, including chewable tablets, extended-release formulations, effervescent tablets, and even in chewing gums. Aspirin is often prescribed in low, daily doses as a preventative measure for individuals at risk for heart attack and stroke.

While aspirin has many medical benefits, it is not without risk for some individuals. Some people are allergic to the compound and can not tolerate even a low dose. Such individuals experience a number of symptoms if they ingest high doses of aspirin, symptoms that include ringing in the ears, nausea, vomiting, dizziness, confusion, hallucinations, coma, seizures, rapid breathing, fever, and, in the most severe cases, death. Aspirin use is not recommended in children under the age of twelve who show symptoms of viral infections because it can lead to an extremely rare but deadly complication known as Reye's syndrome." 4

Physical Properties

Melting Point:*
135°C 5 = 408.15 K = 275°F

* - 1 atm pressure


slightly soluble:  5
soluble:  • 5
very soluble:  5


Double Bonds: 5
Triple Bonds: 0
Sigma Bonds: 21
Pi Bonds: 5
Total: 26
Carboxyl Groups: 1
Hydroxyl Groups: 0


For More Information


(1) - Brownlee, Raymond B., Fuller, Robert W., and Whitsit, Jesse E. Elements of Chemistry; Allyn and Bacon: Boston, Massachusetts, 1959; p 322.
(2) - The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals, 13th ed.; Budavari, S.; O'Neil, M.J.; Smith, A.; Heckelman, P. E.; Kinneary, J. F., Eds.; Merck & Co.: Whitehouse Station, NJ, 2001; entry 856.
(3) - Beer, Alan E. Is Your Body Baby Friendly?; AJR Publishing: Hialeah, Florida, 2009; pp 151-152.
(4) - Schlager, Neil, Weisblatt, Jayne, Newton, David E., and Montney, Charles B. Chemical Compounds Vol. 1; Thomson-Gale: Detroit, MI, 2006; p 34.
(5) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 3-69.
(6) - Kotz, John C. and Treichel, Paul. Chemistry & Chemical Reactivity 4th ed.; Thomson Brooks/Cole: Belmont, CA, 1999; p 163.