Aspirin Uses, Dosage, Side Effects, Food Interaction and all others data.

By decreasing platelet aggregation, Aspirin inhibits thrombus formation on the arterial side of the circulation, where thrombi are formed by platelet aggregation and anticoagulants have little effect. Aspirin is the analgesic of choice for headache, transient musculoskeletal pain and dysmenorrhoea. It has anti-inflammatory and antipyretic properties, which may be useful. Enteric coating reduces the intestinal disturbance and gastrointestinal ulceration due to aspirin.

Effects on pain and fever

Aspirin disrupts the production of prostaglandins throughout the body by targeting cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) . Prostaglandins are potent, irritating substances that have been shown to cause headaches and pain upon injection into humans. Prostaglandins increase the sensitivity of pain receptors and substances such as histamine and bradykinin. Through the disruption of the production and prevention of release of prostaglandins in inflammation, this drug may stop their action at pain receptors, preventing symptoms of pain. Aspirin is considered an antipyretic agent because of its ability to interfere with the production of brain prostaglandin E1. Prostaglandin E1 is known to be an extremely powerful fever-inducing agent .

Effects on platelet aggregation

Trade Name Aspirin
Generic Acetylsalicylic acid
Acetylsalicylic acid Other Names Acetylsalicylate, Acetylsalicylsäure, Acide acétylsalicylique, ácido acetilsalicílico, Acidum acetylsalicylicum, Aspirin, Aspirina, Azetylsalizylsäure, Polopiryna, Salicylic acid acetate
Weight 300mg, 75mg, , 1200mg, 125mg, 325mg, 600mg, 770mg + 60mg + 50mg, 194mg + 227mg + 33mg, 250mg + 250mg + 65mg, 325mg + 50mg + 40mg, 325mg + 50mg + 40mg + 30mg, 325mg + 200mg + 16mg, 325mg + 2mg + 7.8mg, 500mg
Type Tablet, Rectal Suppository, Rectal, Oral Tablet, Oral Capsule, Effervescent, Oral
Formula C9H8O4
Weight Average: 180.1574
Monoisotopic: 180.042258744
Protein binding

50% to 90% of a normal therapeutic concentration salicylate (a main metabolite of acetylsalicylic acid ) binds plasma proteins, particularly albumin, while acetylsalicylic acid itself binds negligibly . Acetylsalicylic acid has the ability to bind to and acetylate many proteins, hormones, DNA, platelets, and hemoglobin .

Groups Approved, Vet approved
Therapeutic Class Anti-platelet drugs
Manufacturer Ideal Pharmaceutical Industries, Premier Pharmaceuticals Ltd, Therapeutics Bangladesh Ltd, United Chemicals &amp, Pharmaceuticals Ltd, Albion Pharmaceuticals Ltd, Apollo Pharmaceutical Laboratories Ltd, Biogene Pharma Ltd, Essential Drugs Company Ltd, Alliance Pharmaceuticals, Bayer Indonesia, Biopharma Nigeria Limited
Available Country Pakistan, Bangladesh, United Kingdom, Canada, United States, Indonesia, Switzerland, Nigeria
Last Updated: September 19, 2023 at 7:00 am


Aspirin is used for its antiplatelet activity in the initial treatment of cardiovascular disorders such as angina pectoris and myocardial infarction and for the prevention of cardiovascular events in a variety of conditions or procedures for patients at risk.

  • Aspirin is used as part of the initial treatment of unstable angina.
  • It is given in the early treatment of myocardial infarction.
  • It may also be of some benefit in the initial treatment of acute ischaemic stroke.
  • It is of value for the secondary prevention of cardiovascular events in patients with stable or unstable angina or those with acute or prior myocardial infarction.
  • Aspirin reduces the risk of future serious vascular events, including stroke, in patients who have already suffered an ischaemic stroke or transient ischaemic attack.
  • It is of use in the long-term management of atrial fibrillation, for the prevention of stroke in patients with contraindications to warfarin or if there are no other risk factors for stroke.
  • It is recommended for use in preventing thrombotic complications associated with procedures such as angioplasty and coronary bypass grafting.

Aspirin is also used to associated treatment for these conditions: Acute Coronary Syndrome (ACS), Anxiety, Arthritis, Atherothrombotic cerebral infarction, Cardiovascular Disease (CVD), Cardiovascular Events, Cardiovascular Mortality, Colorectal Adenomas, Colorectal Cancers, Common Cold, Coronary artery reocclusion, Death, Dyspeptic signs and symptoms, Fever, Flu Like Symptom, Flu caused by Influenza, Headache, Heterozygous Familial Hypercholesterolemia, Inflammation, Juvenile Idiopathic Arthritis (JIA), Kawasaki Syndrome, Major Adverse Cardiovascular and Cerebrovascular Events (MACCE), Migraine, Morbidity, Mucocutaneous Lymph Node Syndrome, Muscle Contraction, Myocardial Infarction, Myocardial Infarction (MI), first occurrence, Neuralgia, Pain, Pain caused by Common Cold, Pain, Menstrual, Pericarditis, Polycythemia Vera (PV), Preeclampsia, Rheumatic Pain, Rheumatism, Rheumatoid Arthritis, Rhinosinusitis, Severe Pain, Soreness, Muscle, Spondyloarthropathies, Stroke, Systemic Lupus Erythematosus (SLE), Tension Headache, Thromboembolism, Toothache, Transient Ischemic Attack, Venous Thromboembolism, Acute Inflammation, Atherothrombotic events, Death by myocardial infarction, Moderate Pain, Thrombotic events, Antiplatelet Therapy, Hemodialysis Treatment, Secondary Prevention

How Aspirin works

Aspirin (ASA) blocks prostaglandin synthesis. It is non-selective for COX-1 and COX-2 enzymes . Inhibition of COX-1 results in the inhibition of platelet aggregation for about 7-10 days (average platelet lifespan). The acetyl group of acetylsalicylic acid binds with a serine residue of the cyclooxygenase-1 (COX-1) enzyme, leading to irreversible inhibition. This prevents the production of pain-causing prostaglandins. This process also stops the conversion of arachidonic acid to thromboxane A2 (TXA2), which is a potent inducer of platelet aggregation . Platelet aggregation can result in clots and harmful venous and arterial thromboembolism, leading to conditions such as pulmonary embolism and stroke.

It is important to note that there is 60% homology between the protein structures of COX-1 and COX-2. ASA binds to serine 516 residue on the active site of COX-2 in the same fashion as its binding to the serine 530 residue located on the active site of COX-1. The active site of COX-2 is, however, slightly larger than the active site of COX-1, so that arachidonic acid (which later becomes prostaglandins) manages to bypass the aspirin molecule inactivating COX-2 . ASA, therefore, exerts more action on the COX-1 receptor rather than on the COX-2 receptor . A higher dose of acetylsalicylic acid is required for COX-2 inhibition .


Aspirin dosage

Pain, Inflammatory diseases and as Antipyretic: Aspirin 300 mg 1-3 tablets 6 hourly with a maximum daily dose of 4 g.

Thrombotic cerebrovascular or Cardiovascular disease: Aspirin 300 mg 1 tablet or Aspirin 75 mg 4 tablets daily.

After Myocardial infarction: Aspirin 75 mg 2 tablets daily for 1 month.

Following By-pass surgery: Aspirin 75 mg 1 tablet daily.

Side Effects

Side effects for usual dosage of Aspirin are mild including nausea, dyspepsia, gastrointestinal ulceration and bronchospasm etc.


Lethal doses

Acute oral LD50 values have been reported as over 1.0 g/kg in humans, cats, and dogs, 0.92 g/kg - 1.48 g/kg in albino rats, 1.19 g/kg in guinea pigs, 1.1 g/kg in mice, and 1.8 g/kg in rabbit models .

Acute toxicity

Salicylate toxicity is a problem that may develop with both acute and chronic salicylate exposure . Multiple organ systems may be affected by salicylate toxicity, including the central nervous system, the pulmonary system, and the gastrointestinal system. Severe bleeding may occur. In the majority of cases, patients suffering from salicylate toxicity are volume-depleted at the time of presentation for medical attention. Fluid resuscitation should occur immediately and volume status should be monitored closely. Disruptions in acid-base balance are frequent in ASA toxicity .

The acute toxicity of acetylsalicylic in animals has been widely studied. The signs of poisoning in rats from lethal doses are mild to severe gastroenteritis, hepatitis, nephritis, pulmonary edema, encephalopathy, shock and some toxic effects on other organs and tissues. Mortality has been observed following convulsions or cardiovascular shock. An important differentiating property between various animal species is the ability to vomit toxic doses. Humans, cats and dogs have this ability, but rodents or rabbits do not .

Chronic toxicity and carcinogenesis

Chronic ASA toxicity is frequently accompanied by atypical clinical presentations that may be similar to diabetic ketoacidosis, delirium, cerebrovascular accident (CVA), myocardial infarction (MI) or cardiac failure. Plasma salicylate concentrations should be measured if salicylate intoxication is suspected, even if there no documentation available to suggest ASA was ingested. In older age, nephrotoxicity from salicylates increases, and the risk of upper gastrointestinal hemorrhage is increased, with higher rates of mortality . It is also important to note that ASA toxicity may occur even with close to normal serum concentrations. Prevention of chronic ASA includes the administration of smallest possible doses, avoidance of concurrent use of salicylate drugs, and therapeutic drug monitoring. Renal function should be regularly monitored and screening for gastrointestinal bleeding should be done at regular intervals .

Chronic toxicity studies were performed in rodents. ASA was administered at doses measured to be 2 to 20 times the maximum tolerated clinical dose to mice for up to one year. Negative dose-related effects were seen. These include decreased mean survival time, decreased number of births and progeny reaching an appropriate age for weaning. No evidence of carcinogenesis was found in 1-year studies . At daily doses of 0.24 g/kg/day given for 100 days to albino rats, ASA led to signs to excessive thirst, aciduria, diuresis, drowsiness, hyperreflexia, piloerection, changes in respiration, tachycardia, followed by soft stools, epistaxis, sialorrhea, dacryorrhea and mortality during hypothermic coma in the second study month .

Use in pregnancy and lactation

While teratogenic effects were observed in animals nearly lethal doses, no evidence suggests that this drug is teratogenic in humans . It is advisable, however, to avoid ASA use the first and second trimester of pregnancy, unless it is clearly required. If acetylsalicylic acid containing drugs are ingested by a patient attempting to conceive, or during the first and second trimester of pregnancy, the lowest possible dose at the shortest possible duration should be taken . This drug is contraindicated in the 3rd trimester of pregnancy .


It should be administered cautiously in asthma, uncontrolled blood pressure and pregnant women.It is specially important not to use aspirin during the last 3 months of pregnancy unless specifically directed to do so by a doctor because it may cause problems in unborn child or complication during delivery. It should be administered with caution to patients in nasal polyp and nasal allergy. Aspirin penetrates into breast milk. So, it should be administered with caution to lactating mothers.


Salicylates may enhance the effect of anticoagulants, oral hypoglycaemic agents, phenytoin and sodium valporate. They inhibit the uricosuric effect of probenecid and may increase the toxicity of sulphonamides. They may also precipitate bronchospasm or induce attacks of asthma in susceptible subjects.

Food Interaction

  • Avoid alcohol. Alcohol increases the risk of gastrointestinal bleeding.
  • Avoid herbs and supplements with anticoagulant/antiplatelet activity. Examples include garlic, ginger, bilberry, danshen, piracetam, and ginkgo biloba.
  • Take after a meal. This reduces irritating gastrointestinal effects.
  • Take with a full glass of water.

Volume of Distribution

This drug is distributed to body tissues shortly after administration. It is known to cross the placenta. The plasma contains high levels of salicylate, as well as tissues such as spinal, peritoneal and synovial fluids, saliva and milk. The kidney, liver, heart, and lungs are also found to be rich in salicylate concentration after dosing. Low concentrations of salicylate are usually low, and minimal concentrations are found in feces, bile, and sweat .

Elimination Route

Absorption is generally rapid and complete following oral administration but absorption may be variable depending on the route, dosage form, and other factors including but not limited to the rate of tablet dissolution, gastric contents, gastric emptying time, and gastric pH .

Detailed absorption information

When ingested orally, acetylsalicylic acid is rapidly absorbed in both the stomach and proximal small intestine. The non-ionized acetylsalicylic acid passes through the stomach lining by passive diffusion. Ideal absorption of salicylate in the stomach occurs in the pH range of 2.15 - 4.10. Intestinal absorption of acetylsalicylic acid occurs at a much faster rate. At least half of the ingested dose is hydrolyzed to salicylic acid in the first-hour post-ingestion by esterases found in the gastrointestinal tract. Peak plasma salicylate concentrations occur between 1-2 hours post-administration .

Half Life

The half-life of ASA in the circulation ranges from 13 - 19 minutes. Blood concentrations drop rapidly after complete absorption. The half-life of the salicylate ranges between 3.5 and 4.5 hours .


The clearance rate of acetylsalicylic acid is extremely variable, depending on several factors . Dosage adjustments may be required in patients with renal impairment . The extended-release tablet should not be administered to patients with eGFR of less than 10 mL/min .

Elimination Route

Excretion of salicylates occurs mainly through the kidney, by the processes of glomerular filtration and tubular excretion, in the form of free salicylic acid, salicyluric acid, and, additionally, phenolic and acyl glucuronides .

Salicylate can be found in the urine soon after administration, however, the entire dose takes about 48 hours to be completely eliminated. The rate of salicylate is often variable, ranging from 10% to 85% in the urine, and heavily depends on urinary pH. Acidic urine generally aids in reabsorption of salicylate by the renal tubules, while alkaline urine increases excretion .

After the administration of a typical 325mg dose, the elimination of ASA is found to follow first order kinetics in a linear fashion. At high concentrations, the elimination half-life increases .

Pregnancy & Breastfeeding use

Aspirin should be avoided during the last 3 months of pregnancy. As aspirin is excreted in breast milk, aspirin should not be taken by patients who are breast-feeding.


Aspirin is contraindicated to the children (Reye's syndrome) under 12 years, in breast-feeding and active peptic ulcer. It is also contraindicated in bleeding due to haemophilia and other ulceration. Hypersensitivity to aspirin, hypoprothrombinaemia is also contraindicated

Acute Overdose

Overdosage produces dizziness, tinnitus, sweating, nausea and vomiting, confusion and hyperventilation. Gross overdosage may lead to CNS depression with coma, cardiovascular collapse and respiratory depression. If overdosage is suspected, the patient should be kept under observation for at least 24 hours, as symptoms and salicylate blood levels may not become apparent for several hours. Treatment of overdosage consists of gastric lavage and forced alkaline diuresis. Haemodialysis may be necessary in severe cases.

Storage Condition

Store in a cool and dry place, protected from light.

Innovators Monograph

You find simplified version here Aspirin

Aspirin contains Acetylsalicylic acid see full prescribing information from innovator Aspirin Monograph, Aspirin MSDS, Aspirin FDA label


What is Aspirin used for?

Aspirin is a pharmaceutical drug used to reduce pain or inflammation. It is classified as a non-steroidal anti-inflammatory drug (NSAID).Aspirin can be used to treat, mild to moderate pain.

How safe is Aspirin?

Safety issues related both to the risk of bleeding and to that of developing rare but serious liver and brain damage mostly among children  should be considered.

How does Aspirin work?

Aspirin works by blocking the production of prostaglandins, the on-off switch in cells that regulate pain and inflammation, among other things.

What are the common side effects of Aspirin?

The common side effects of Aspirin are include:

  • ringing in your ears, confusion, hallucinations, rapid breathing, seizure (convulsions);
  • severe nausea, vomiting, or stomach pain;
  • bloody or tarry stools, coughing up blood or vomit that looks like coffee grounds;
  • fever lasting longer than 3 days; or
  • swelling, or pain lasting longer than 10 days.

Is Aspirin safe during pregnancy?

Experts caution against taking adult Aspirin during pregnancy because studies have linked it to various complications. A few studies show that taking Aspirin around the time of conception and in early pregnancy is associated with an increased risk of miscarriage.

What happens if I take Aspirin while pregnant?

Taking higher doses of Aspirin during the third trimester increases the risk of the premature closure of a vessel in the fetus's heart. Use of high-dose Aspirin for long periods in pregnancy also increases the risk of bleeding in the brain of premature infants.

Is Aspirin safe during breastfeeding?

Aspirin is best avoided during breastfeeding; however, some expert opinion indicates that low-dose Aspirin may be considered as an antiplatelet drug for use in breastfeeding women.

Can I drink alcohol with Aspirin?

Do not drink alcohol while taking Aspirin. Alcohol can increase your risk of stomach bleeding caused by Aspirin.

When should I take Aspirin?

Take low-dose aspirin once a day. Don't take it on an empty stomach. It's best to take it with or just after food. This will make it less likely to upset your stomach.

When should I take my Aspirin morning or night?

There is a body of research that suggests the majority of heart attacks occur in the morning. So taking Aspirin before bedtime may be the better bet as it allows time for the medication to thin the blood, which reduces the risk of heart attack.

When should not I take Aspirin?

Adults who are 60 and older should not start taking aspirin to lower their risk of a first heart attack or stroke.

Can Aspirin make me sleepy?

Common Aspirin side effects may include upset stomach, heartburn; drowsiness; or. headach.

Does aspirin raise blood pressure?

Aspirin is a nonsteroidal anti-inflammatory drug (NSAID).Aspirin can actually raise blood pressure in people with hypertension.

What are the benefits of taking Aspirin?

Everyday uses include relieving headache, reducing swelling, and reducing a fever. Taken daily, Aspirin can lower the risk of cardiovascular events, such as a heart attack or stroke, in people with a high risk.

How can I protect my stomach from Aspirin?

A way for most of us to reduce the possibility of stomach ulcers is to take the Aspirin with a half glass of warm water before and another half glass of warm water surrounding taking the Aspirin. And take the Aspirin one or two hours after eating.

How many Aspirin can I take a day?

The researchers conclude that the optimal daily dose of aspirin therapy is between 75 mg and 100 mg a day.

Can I take Aspirin daily?

Don't start taking a daily Aspirin without talking to your health care provider. While taking an occasional Aspirin or two is safe for most adults to use for headaches, body aches or fever, daily use of Aspirin can have serious side effects, including gastrointestinal bleeding.

Is Aspirin bad for kidneys?

When taken as directed, regular use of Aspirin does not seem to increase the risk of kidney disease in people who have normal kidney function. However, taking doses that are too large may temporarily and possibly permanently reduce kidney function.

How long does Aspirin stay in my body?

It takes a full 10 days for aspirin's effects to wear off after a person stops taking it.

Can Aspirin cause kidney stones?

Certain Aspirin may increase your risk of developing recurrent kidney stones.

What should I do if I forget a dose of Aspirin?

If your doctor has told you to take Aspirin on a regular basis and you miss a dose, take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

What happens if I overdose of Aspirin?

If you or someone around you has taken a potentially toxic dose of Aspirin, or you suspect an Aspirin overdose for another reason, you must seek emergency medical care as soon as possible or call your local emergency number.
*** Taking medicines without doctor's advice can cause long-term problems.