Ibuprofen and  Acetaminophen  are medications used for treating similar conditions. However there are differences between the two. For instance, Acetaminophen is used for treating pain and fever, whereas Ibuprofen is used for treating pain, fever and inflammation. This makes these two medications useful for treating conditions of the same category but with changes within the category. Here is an in-depth look at the differences between both medications for a better understanding of the similarities and the differences between the two.


Here is a detailed description of Ibuprofen, along with the mechanism of action and the manner in which it interacts with the human body.

Belonging to the category of non-steroidal anti-inflammatory drugs, Ibuprofen is a derivative of propionic acid. It was first developed more than 60 years ago, and the propionic was the result of a search for an option other than aspirin which was widely used at that time. Initially used for treating rheumatoid arthritis, Ibuprofen received its patent in the year 1961 and has the distinction of being the first non-steroidal anti-inflammatory drug to be made available as OTC medication.

Conditions for which Ibuprofen is typically prescribed

Among the non-steroidal anti-inflammatory drugs that are prescribed, Ibuprofen is the most frequently prescribed medication. Additionally it also happens to be the most commonly used OTC medication for its distinct analgesic, antipyretic and anti-inflammatory properties. It is generally used as a racemic mixture for managing pain as a result of migraine, spondylitis, rheumatoid arthritis, dysmenorrhea, headache, pain due to dental procedures, and osteoarthritis among others.

It is mainly prescribed for therapeutic effects that include the following conditions :

· Neonatal condition – the blood vessel which serves as a connection between the primary pulmonary artery and the proximal aorta sometimes does not close after childbirth. As a consequence of this, there is a possibility of heart failure, and this condition is known as patent ductus arteriosus. Ibuprofen has been used for treating this condition, mainly because prostaglandin E2 is responsible for keeping the blood vessel open. Since Ibuprofen is known to act against prostaglandin E2, it is used for treating this condition.

· Inflammatory, musculoskeletal disorders – Ibuprofen was first used for treating rheumatic arthritis, and it is frequently used for treating various musculoskeletal disorders and inflammatory disorders.

· Fibrosis of the lungs – Ibuprofen is used for treating inflammation and to reduce the polymorphonuclear cells in the lungs. The non-steroidal anti-inflammatory drug is commonly used for treating cystic fibrosis.

· Pain as a result of dental procedures – individuals who undergo dental procedures typically experience orofacial pain that could be either acute in nature or chronic, depending on the condition. Ibuprofen is used for pain management in patients who have undergone dental procedures.

· Pain experienced routinely – the non-steroidal anti-inflammatory drug is also used for managing pain that is experienced commonly. It is also typically used to reduce fever, apart from managing dysmenorrhea.

· Reduction of sodium – Ibuprofen has been used in patients with orthostatic hypotension, as the non-steroidal anti inflammatory drug triggers sodium retention and works as an antagonist for diuretics. This makes it suitable for treating the condition.

Ibuprofen pharmacodynamics

The non-steroidal anti-inflammatory drug works in different ways in the various inflammatory pathways that are responsible for inflammation. Mechanism of action of Ibuprofen results primarily in the reduction of inflammation that is both chronic and acute. This is achieved by inhibiting the COX-1 and COX-2 from synthesizing prostanoids. Pain regulation from the medication is attributed to the mediation of pain transmission in the affected region and the central nervous system. There are other possibilities attributed to pain management. This includes the action on the NMDA receptors.

Additionally the antipyretic effects of Ibuprofen is attributed to the effect of the non-steroidal anti-inflammatory drug on prostanoid synthesis. By virtue of being the primary signaling mediator, prostanoids are one of the main reasons for pyresis. Patients who undergo dental procedures are more likely to experience pain. Ibuprofen is used for pain management after dental procedures, and its effect is mainly as a result of the inhibition of prostanoid production. Additionally, Ibuprofen has anti-oedimic activity, apart from increasing plasma beta- endorphins.

The medication is widely used for treating patients’ musculoskeletal conditions, and various rheumatic diseases. It is used for managing dysmenorrhea, and for bringing about introduction in the menstrual prostanoids, apart from uterine hypercontractility, which helps in managing the condition effectively. Ibuprofen has been effectively used for managing the symptoms associated with migraines. The mechanism of action is primarily attributed to platelet activation and the production of thromboxane A2, which is known to trigger vascular effects in the regions that are affected. Since Ibuprofen enters the central nervous system, this effect is triggered, which helps in treating the condition.

Mechanism of action of Ibuprofen

While there is no conclusive evidence of the actual mechanism of action of Ibuprofen, studies have indicated and suggested the manner in which the non steroidal anti-inflammatory drug acts. As a non-selective inhibitor of cyclooxygenase, it possesses properties that make it effective in managing pain, inflammation and fever. This is attributed to the inhibition of cyclooxygenase that is responsible for triggering the prostaglandin synthesis and thromboxane synthesis.

By virtue of being a non-selective cyclooxygenase inhibitor, it has an impact on the activity of COX-1 as well as COX-2. Consequently, inhibition of COX2 brings down the effect of prostaglandins that are responsible for pain, fever and inflammation.

Rate of absorption of Ibuprofen

The non steroidal anti inflammatory drug has strong absorption rate, and achieves peak serum concentration within 2 hours from the time of being administered. Studies have revealed that the rate of absorption of Ibuprofen reduces marginally when it is administered after a meal. Though the rate of absorption is reduced in this condition, it does not have any impact on the amount of absorption that occurs. In other words, the amount of absorption is the same before and after a meal, but the rate of absorption difference in both the conditions.

Metabolism of Ibuprofen

The non steroidal anti inflammatory drug has the property of being very quickly metabolized. It is bio transformed in the liver resulting in various derivatives. The metabolism of Ibuprofen can be split into 2 different phases. The first phase is the hydroxylation, which results in the formation of hydroxy derivatives. The second phase is when the oxidative metabolism results in the formation of phenolic and acyl glucuronides.

The elimination route of Ibuprofen

The non steroidal anti inflammatory drug undergoes fast metabolization and it is expelled from the body by urine. As a result the process accounts for as much as 90% of the administered dose. Ibuprofen is fully cleared from the body in 24 hours, from the time the last dose is administered. By virtue of the rapid metabolization, most of the administered dose passes through the process of metabolization. The amount of Ibuprofen that is excreted in the same form when it was administered is just one percent of the total administered dosage. There is no impact on the excretion of Ibuprofen from any medical or age related condition.

The half life of Ibuprofen

The non-steroidal anti-inflammatory drug has a serum of life that is between 1.2 hours to 2 hours. This could be as much as 3.1 hours to 3.4 hours in patients who have certain liver conditions.

Ibuprofen toxicity

Individuals who have consumed more than the prescribed dosage of Ibuprofen are likely to experience overdose symptoms. For instance whenever the dosage exceeds 99 mg/kg, there is a likelihood of experiencing overdose symptoms. Some of the commonly reported symptoms as a result of overdose include dizziness, drowsy feelings, vomiting and nausea, pain in the abdomen, vertigo and an overall lazy feeling. Additionally there are other symptoms associated with overdose of Ibuprofen. This includes possible loss of consciousness, seizures, tinnitus, throbbing pain in the head and convulsions. In a very limited number of cases, this results in respiratory problems, renal failure, unusual hepatic function, and coma.


Here is a description of Acetaminophen which is one of the commonly used analgesics globally. It is used as a first line treatment for managing pain, and this is attributed to the antipyretic effects that help to reduce fever. Approved by the FDA almost seven decades ago, Acetaminophen is presently available in various forms. Available as oral medication, injectables, suppository and as a syrup, Acetaminophen commonly known as paracetamol is one among the most commonly used medications.

The medication is typically used as an active ingredient in combination drugs used for treating allergies and colds, and for managing pain and helping induce sleep. The drug is presently part of more than 600 different combination medications used for the above conditions. One of the reasons for the confusion about the suitable dosage of the medication, is attributed to the availability of the medication in different formulations. As a consequence of the overdosing attributed to Acetaminophen, individuals are advised to strictly adhere to dosage guidelines when taking the medication.

Conditions for which Acetaminophen is prescribed

Acetaminophen is typically used for treating pain and to bring down fever. Available as over the counter medication, the most popular form of Acetaminophen is oral. Injections are typically used for managing moderate or severe pain and for bringing down fever. Injections are generally used as adjunct medication alongside opioid analgesics.

Pharmacodynamics of Acetaminophen

The identified properties of Acetaminophen include analgesic effects and antipyretic effects. However, the medication does not deliver any anti-inflammatory action. This is one of the main differences between Acetaminophen and Ibuprofen. Unlike the salicylate class of drugs, Acetaminophen does not have any impact on the acid base balance when the ideal dosage recommendations are followed. It is also not known to have any impact on the tubular secretion of uric acid unlike the salicylate class of drugs. It also does not possess any inhibitory properties against platelet aggregation, and it also does not have any disruptive effect on hemostasis. The possibility of allergic reactions as a result of Acetaminophen are extremely rare.

Mechanism of action of Acetaminophen

The precise mechanism of action of Acetaminophen has not been exactly identified. It belongs to the category of non steroidal anti inflammatory drugs by virtue of inhibiting the cyclooxygenase pathways. The medication brings about mitigation of pain as a result of its inhibitory actions in the COX pathways. Among the various possibilities that have emerged from studies, the first theory suggest that Acetaminophen helps to expand the ability to manage pain by inhibiting the COX-1 and COX-2. This is in turn involved in the synthesis of prostaglandins that are known to be responsible for mediating various pain sensations. Acetaminophen is not known to have any inhibitory action on cyclooxygenase in the peripheral tissues. Consequently, the medication does not have any impact on peripheral inflammation. Acetaminophen is known to block COX indirectly. Studies reveal that Acetaminophen is a selective inhibitor of prostaglandins. It selectively blocks a particular variant of COX enzyme, that is unlike the usual COX-1 and COX-2 variants. Commonly known as COX-3, the inhibition of this enzyme is responsible for the antipyretic actions of Acetaminophen. The action is also attributed to the vasodilation and perspiration which has an impact on the heat regulating centres of the brain, by loss of body heat.

Rate of absorption of Acetaminophen

With 88% bioavailability, Acetaminophen is known to achieve high plasma concentration within 1 and half hours of being administered orally. The rate of absorption differs when it is administered rectally as a suppository. It takes as much as 3 hours for Acetaminophen to achieve peak blood levels when it is administered rectally. Additionally, the peak blood concentration levels differ between the various forms of administration. For instance when Acetaminophen is administered rectally, it achieves peak blood concentration which is only 50% of the concentration levels achieved when administered orally.

The bioavailability of Acetaminophen depends on the manner in which it is administered. This is precisely why it may be necessary to increase the dose of Acetaminophen when administered rectally. This will help to achieve higher blood concentration levels, which would be similar to that of blood concentration levels after administration of Acetaminophen orally.

Metabolism of Acetaminophen

Non steroidal anti inflammatory drug is metabolized in the liver, through three different pathways. Consequent to this metabolism, a reactive metabolite is produced. When Acetaminophen is administered in the right/recommended doses, it is safe. However when Acetaminophen is administered in higher doses, the reactive metabolite has an impact on the liver. This is typically pre-empted by administration of certain compounds to mitigate the action.

Elimination route of Acetaminophen

Acetaminophen is eliminated in urine with 90% of the dosage leaving the body as conjugated Acetaminophen, with less than 5% leaving the body as free Acetaminophen.

Half life of Acetaminophen

When administered intravenously, the half life of Acetaminophen is 2.5 hours, while the afterlife could be anywhere between 4 hours to 8 hours when there is an overdose.

Acetaminophen toxicity

As a result of overdose of Acetaminophen, there is a possibility of tubular necrosis and thrombocytopenia. It is also possible that the individual may go into hypoglycemic coma, and experience liver necrosis. Serious complications from Acetaminophen are attributed to the release of a toxic metabolic that is commonly known as NAPQI. Some of the possible outcomes of the toxicity of Acetaminophen include the following.

Carcinogenic risk has been observed in studies conducted over 2 years. There was clear evidence of carcinogenic activity which was higher than the safe daily limits.

The drug does not have any impact on fertility, as per the results of a study conducted in Switzerland, Acetaminophen is classified as category C drug for pregnancy, which means that it has known side effects, from studies conducted on animals. While similar clinical studies on humans have not been conducted, is it has been recommended to be used only when absolutely necessary on pregnant women. While there is no data to suggest that use of Acetaminophen has an impact, studies have shown that secretions of Acetaminophen have been observed in nursing mothers. This makes it important to carefully administer the non steroidal anti inflammatory drug on nursing mothers.

Comparison of Acetaminophen and Ibuprofen

Acetaminophen is generally used to treat pain and fever, while Ibuprofen is typically used for treating pain inflammation and fever. Both the medications are available as over-the-counter and prescription formulations. While Ibuprofen and Acetaminophen belong to the same category (non steroidal anti-inflammatory drugs), each is suitable for treating specific conditions, and are not to be used interchangeably.

Both Acetaminophen and Ibuprofen are not to be used with alcohol, as it is likely to increase the risk of side effects. For instance, alcohol can aggravate the risk factors, resulting in heightened risk of liver damage, and bleeding when taken in combination with other Ibuprofen or Acetaminophen. Among both medications, Acetaminophen has stronger adverse effects on the liver than Ibuprofen. This is attributed to the fact that Acetaminophen is processed in the liver and like Ibuprofen which is not heavily processed or metabolized in the liver. While both Acetaminophen and Ibuprofen belong to the same category of non steroidal anti-inflammatory drugs, they are often prescribed to be taken as combination medication, for specific pain management conditions.


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