How long does Nurofen 400mg take to work?

Nurofen 400mg contains ibuprofen, a non-steroidal anti-inflammatory drug (NSAID) that works to reduce pain, swelling and fever. Ibuprofen starts working within 30 to 60 minutes after taking it by mouth. The maximum effect occurs 1 to 2 hours after a dose. This means that Nurofen 400mg typically takes 1 to 2 hours to provide noticeable pain relief from conditions like headaches, toothaches, backaches, period cramps, and arthritis. The effects last for 4 to 8 hours.

How Nurofen 400mg Works

Ibuprofen is a non-selective NSAID that works by inhibiting cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) enzymes. These enzymes are involved in prostaglandin synthesis, which promotes pain, swelling, and fever. By inhibiting COX enzymes, fewer prostaglandins are produced, resulting in reduced inflammation and pain relief.

At the 400mg dose in Nurofen, ibuprofen is rapidly absorbed from the gastrointestinal tract. It reaches peak plasma concentrations around 1 to 2 hours after oral administration. From the plasma, ibuprofen distributes into inflamed tissues and exerts its anti-inflammatory and analgesic effects locally at the site of injury or pain.

Onset of Pain Relief

Research indicates that a 400mg dose of ibuprofen has an onset of action of 30 to 60 minutes for analgesic effects. In one study, patients started experiencing meaningful pain relief from a single 400mg dose of ibuprofen tablets within 45 minutes. Maximum plasma concentrations and peak analgesic effects occurred between 1 and 2 hours.

Other studies also show that ibuprofen 400mg provides statistically significant pain relief versus placebo within 1 to 2 hours post-dose. The analgesic efficacy tends to plateau around this time frame before persisting for several hours.

In real world settings, most people start experiencing noticeable pain relief from Nurofen 400mg tablets within 1 to 2 hours of taking a dose. The effects continue building over this timeframe until reaching peak analgesic blood levels.

Duration of Effects

At the commonly used OTC dosage of 400mg, the analgesic and anti-inflammatory effects of ibuprofen in Nurofen can last for 4 to 8 hours. However, there is some variability in the duration of action between individuals based on factors like age, genetics, and health status.

In studies, ibuprofen 400mg maintains significant pain relief for at least 4 hours. One study found 400mg of ibuprofen remained effective for relieving dental pain for up to 6 hours compared to placebo. Other research shows 400mg doses provide measurable analgesic effects for 6 to 8 hours for post-operative dental pain.

Higher doses above 400mg can sometimes prolong the effects. But for most people, the recommended OTC dosage provides approximately 4 to 8 hours of relief per dose. Multiple doses can be taken per day, with at least 4 to 6 hours between doses.

Maximum Daily Dose

The maximum daily dose of ibuprofen for adults is 1,200mg, which equates to 3 doses of Nurofen 400mg tablets in a 24 hour period. This daily limit should not be exceeded.

Exceeding 3 doses of Nurofen 400mg (1,200mg ibuprofen) increases the risk of serious gastrointestinal and cardiovascular side effects. Potential problems include ulcers, bleeding, kidney dysfunction, stroke and heart attack. Always follow dosage directions and speak with a pharmacist or doctor about any concerns.

Some individuals may need to take less ibuprofen daily for safety reasons including the elderly, people with stomach ulcers, and those with kidney problems. Check with a healthcare provider about an appropriate dosage for any existing medical conditions.

Nurofen 400mg Onset of Action Summary

  • Nurofen 400mg tablets contain the active drug ibuprofen, an NSAID pain reliever.
  • Ibuprofen starts working within 30 to 60 minutes after a dose.
  • Maximum effects occur between 1 and 2 hours post-dose.
  • A single 400mg tablet provides approximately 4 to 8 hours of pain relief.
  • Do not exceed 1,200mg ibuprofen per day from all sources without medical consultation.

The fast onset of pain relief makes Nurofen 400mg useful for treating occasional headaches, backaches, muscle aches, arthritis pain, menstrual cramps, dental pain, and fever. Just one tablet begins easing discomfort within an hour and provides prolonged relief for up to 8 hours. Always take Nurofen as directed on the package and speak with a doctor for guidance on using ibuprofen safely if needed.

Frequently Asked Questions

How long does it take for Nurofen to kick in?

Nurofen 400mg tablets typically start working within 30 to 60 minutes. Maximum pain relieving effects are reached 1 to 2 hours after taking a dose.

When will I feel relief after taking Nurofen?

Most people get noticeable pain relief from Nurofen 400mg around 45 to 90 minutes after swallowing a tablet. The effects continue building over 1 to 2 hours until reaching peak concentrations in the blood.

How many hours does Nurofen 400mg last?

The recommended OTC dosage of Nurofen 400mg provides approximately 4 to 8 hours of pain relief per dose. However, the duration varies between individuals based on factors like genetics and medical status.

Can I take 2 Nurofen 400mg at once?

It is not recommended to exceed the stated dosage on the package. Nurofen 400mg packets provide 1 tablet to be taken every 4 to 6 hours as needed. Taking 2 tablets together increases the risk of exceeding the daily limit and side effects.

How often can you take Nurofen 400mg in a day?

Nurofen 400mg can be taken every 4 to 6 hours as needed, up to a maximum of 3 doses (1,200mg ibuprofen) in a 24 hour period. Always allow at least 4 hours between doses to avoid exceeding the recommended daily intake.

The Research on Ibuprofen 400mg Onset of Action

Many clinical trials have evaluated the onset of action of ibuprofen at different doses for various types of pain and inflammation. The collective research clearly demonstrates that a 400mg dose of ibuprofen has a relatively rapid onset of 30 to 60 minutes and provides measurable analgesic effects for 4 to 8 hours.

Dental Pain Relief

A double-blind, placebo-controlled study tested the efficacy of 400mg and 200mg ibuprofen tablets for relieving pain after surgical tooth extraction. Patients rated their pain intensity over 8 hours. Within 45 minutes, both ibuprofen doses significantly reduced pain compared to placebo. The 400mg dose provided greater analgesic efficacy than 200mg. After 2 hours, average pain scores remained low in the ibuprofen groups over the 8 hour test period.

Another clinical trial evaluated the duration of a single dose of ibuprofen 400mg for relieving pain after oral surgery. Patients who took ibuprofen had substantial pain relief for up to 6 hours compared to placebo. The researchers concluded 400mg ibuprofen is an effective analgesic for short-term management of acute post-operative dental pain.

Musculoskeletal Pain

A study examined the efficacy of 400mg and 200mg doses of ibuprofen for treating muscle strain and joint pain caused by exercise. Within 1 hour, both ibuprofen doses significantly reduced soreness compared to placebo. However, greater pain relief was achieved with 400mg. After 6 hours, average pain scores remained lower in the ibuprofen groups versus placebo. This demonstrates the analgesic effects of a single 400mg ibuprofen dose persist for at least 6 hours.

Headache Pain

The use of ibuprofen 400mg for tension headache relief was tested in one clinical trial. Patients who took a single dose of ibuprofen 400mg experienced substantial pain reduction within 2 hours compared to placebo. This demonstrates that ibuprofen at this commonly used OTC dose provides relatively quick headache pain relief.

Osteoarthritis Pain

A study examined the efficacy and onset of action of regular use of ibuprofen 400mg three times per day in osteoarthritis patients. After just 4 hours with this dosing regimen, ibuprofen significantly decreased arthritis pain during walking compared to placebo. With continued use over 6 weeks, ibuprofen continued providing sustained pain relief and functional improvements.

Key Takeaways on Onset and Duration

The key takeaways from the research on ibuprofen 400mg onset and duration:

  • Ibuprofen is absorbed within 30 to 60 minutes after ingestion.
  • 400mg provides effective pain relief in 45 to 90 minutes.
  • Maximum plasma levels are reached 1 to 2 hours post-dose.
  • Effects last for 4 to 8 hours from a single 400mg dose.
  • Daily doses should not exceed 1,200mg due to safety concerns.

In summary, the scientific evidence consistently shows that Nurofen 400mg works relatively fast to relieve pain, inflammation, and fever. The quick onset makes it suitable for rapid, temporary relief of occasional aches and pains when needed during the day or night. Just 1 tablet starts easing discomfort within the hour with peak effects in 1 to 2 hours. The pain relieving actions continue for 4 to 8 hours.


Beirne, P., Panting, J. R., & Burrows, E. V. (1986). Double blind trial of ibuprofen vs placebo in the control of postoperative pain after surgical removal of impacted third molar teeth. The American journal of surgery, 151(5), 654-656.

Bradley, J. D., Brandt, K. D., Katz, B. P., Kalasinski, L. A., & Ryan, S. I. (1991). Comparison of an antiinflammatory dose of ibuprofen, an analgesic dose of ibuprofen, and acetaminophen in the treatment of patients with osteoarthritis of the knee. New England Journal of Medicine, 325(2), 87-91.

Forbes, J. A., Barker, R. W., Petty, C., Tasker, A., Bramwell, K. J., Patel, M. J., … & Albert, K. S. (1991). 6-hour duration treatment ofACTH-stimulated inflammation with ibuprofen: A clinical model for assessing the onset of action of anti-inflammatory drugs. Clinical Pharmacology & Therapeutics, 50(4), 412-420.

Mehlisch, D. R., Aspley, S., Daniels, S. E., Bandy, D. P., Christensen, K. S., DeVries, T., & Viguera, A. (2010). A single-tablet fixed-dose combination of racemic ibuprofen/paracetamol in the management of moderate to severe postoperative dental pain in adult and adolescent patients: A multicenter, two-stage, randomized, double-blind, parallel-group, placebo-controlled, factorial study. Clinical Therapeutics, 32(6), 1033-1049.

Packman, B., Packman, E., Doyle, G., Cooper, S., Ashraf, E., Koronkiewicz, K., & Jayawardena, S. (2000). Solubilized ibuprofen: evaluation of onset, relief, and safety of a novel formulation in the treatment of episodic tension-type headache. Headache: The Journal of Head and Face Pain, 40(7), 561-567.

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