Researchers tested whether an extract from the astragalus plant could help people with knee pain. In a carefully controlled study, 90 adults took either the plant extract or a fake pill for 28 days. The group taking the real extract experienced about 30% less knee pain compared to those taking the fake pill. The results were strong and statistically significant, and no serious side effects were reported. This suggests that astragalus extract might be a safe natural option for people looking to manage knee pain without relying solely on traditional medications.

The Quick Take

  • What they studied: Whether a natural plant extract called astragalus could reduce knee pain in people with functional knee problems
  • Who participated: 90 healthy adults between 18 and 60 years old from a hospital in India. Half received the plant extract and half received a placebo (fake pill) that looked identical
  • Key finding: People taking the astragalus extract had 30% less knee pain after 28 days compared to those taking the placebo. This difference was very strong statistically (p < 0.0001), meaning it’s very unlikely to have happened by chance
  • What it means for you: If you have knee pain, astragalus extract might help reduce discomfort naturally. However, this is one study with a small group, so talk to your doctor before trying it, especially if you take other medications

The Research Details

This was a randomized controlled trial, which is considered one of the strongest types of research studies. Researchers randomly divided 90 participants into two equal groups: one received 480 mg of astragalus extract daily, and the other received a placebo (fake pill) that looked identical. Neither the participants nor the researchers knew who was getting the real extract—this is called “double-blinded” and helps prevent bias. The study lasted 28 days, with pain measurements taken at the start, and then on days 5, 14, and 28.

The researchers measured knee pain using a visual analog scale, which is a simple tool where people rate their pain on a line from 0 (no pain) to 10 (worst pain). They also tested how well people could walk, climb stairs, and move their knees. They checked in with participants multiple times to track progress and watch for any side effects.

This study design is strong because the random assignment and blinding reduce the chances that results were influenced by expectations or bias. The multiple measurement points throughout the month helped show how quickly the extract worked.

Using a randomized controlled trial design is important because it’s the gold standard for testing whether a treatment actually works. By randomly assigning people to groups and keeping both participants and researchers blinded, the study minimizes the placebo effect (where people feel better just because they expect to) and other biases. Multiple measurements over time show whether benefits appear quickly or develop gradually, which is useful information for anyone considering the treatment.

This study has several strengths: it used proper randomization, was double-blinded, measured outcomes multiple times, and reported no serious side effects. However, the sample size of 90 people is relatively small, and all participants were from one hospital in India, so results might not apply equally to everyone worldwide. The study only lasted 28 days, so we don’t know if benefits continue longer or if any problems develop with extended use. The researchers also didn’t compare astragalus to standard pain medications, so we can’t say whether it works better or worse than existing treatments.

What the Results Show

The main finding was that people taking astragalus extract experienced significantly more pain relief than those taking placebo. After the 6-minute walk test, the astragalus group showed a 30% reduction in knee pain, while the placebo group showed minimal improvement. This difference was highly statistically significant (p < 0.0001), meaning there’s less than a 1 in 10,000 chance this happened randomly.

Pain reduction appeared relatively quickly—improvements were visible by day 5 and continued through day 28. The astragalus group also performed better on the stair climb test, suggesting the extract helped with functional activities that involve knee movement. Participants’ knee range of motion (how far they could bend and straighten their knees) also improved more in the astragalus group compared to placebo.

Patient satisfaction was notably higher in the active treatment group, with more people reporting they felt the treatment was helpful. Importantly, the study found no serious adverse events in either group, suggesting the extract was well-tolerated. Compliance was good in both groups, meaning people took their pills as instructed.

Beyond pain reduction, the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC)—a detailed questionnaire about knee function—showed greater improvement in the astragalus group. This measure captures not just pain but also stiffness and difficulty with daily activities. The stair climb test results indicated that participants could perform this challenging movement more easily after taking astragalus, suggesting real-world functional benefits. The improvement in knee range of motion means people could move their knees through a fuller range without discomfort, which is important for activities like walking, sitting, and exercising.

This study adds to growing evidence that traditional plant-based remedies may have measurable benefits for joint health. Astragalus has been used in traditional Chinese medicine for centuries, but high-quality scientific studies testing it are still limited. This randomized controlled trial provides stronger evidence than previous observational studies or case reports. However, most research on astragalus for joint pain is still preliminary, so this study represents an important but early step in understanding its effectiveness. More research is needed to compare it directly with standard pain medications and to test it in larger, more diverse populations.

Several limitations should be considered. First, the study only included 90 people from one hospital in India, so results might not apply equally to people of different ages, backgrounds, or geographic locations. Second, the study lasted only 28 days—we don’t know if benefits continue, decrease, or if any problems develop with longer-term use. Third, researchers didn’t compare astragalus to standard pain medications like ibuprofen or acetaminophen, so we can’t say whether it’s more or less effective than these options. Fourth, the study focused on “functional knee pain” but didn’t specify the underlying cause (arthritis, injury, overuse, etc.), so results might vary depending on what’s causing the pain. Finally, the study didn’t measure how much pain relief participants experienced in their daily lives outside of the specific tests performed.

The Bottom Line

Based on this single study, astragalus extract appears to be a safe option that may help reduce knee pain. However, confidence in this recommendation is moderate because it’s one study with a small group. If you have knee pain, you might discuss astragalus with your doctor as a potential complementary approach, especially if you’re concerned about side effects from standard pain medications. Start with the dose used in this study (480 mg daily) and give it at least 2-4 weeks to see if it helps. Don’t stop taking prescribed medications without talking to your doctor first.

This research is most relevant for adults aged 18-60 with knee pain who are interested in natural alternatives or who experience side effects from standard pain medications. People with arthritis, overuse injuries, or general knee discomfort might find this helpful. However, if you have severe knee pain, significant swelling, or difficulty bearing weight, see a doctor first to rule out serious injuries. Pregnant women, people with immune system disorders, or those taking blood thinners should consult their doctor before trying astragalus, as it may interact with medications or affect immune function.

Based on this study, you might notice some pain reduction within 5 days, with more significant improvement by 2-4 weeks. However, individual responses vary—some people may see faster results while others might need the full month to experience benefits. If you don’t notice improvement after 4 weeks, it may not be the right option for you. Remember that this is one study, so results may differ from person to person.

Want to Apply This Research?

  • Track daily knee pain on a 0-10 scale (0 = no pain, 10 = worst pain) before and after activities like walking, climbing stairs, or exercise. Record this daily in your app to see if the extract reduces pain during these specific activities over 4 weeks
  • Set a daily reminder to take your astragalus supplement at the same time each day. Also track which activities cause knee pain and monitor whether these become easier or more comfortable as you continue the supplement
  • Create a weekly summary in your app showing average pain levels and how your knee function is improving (ability to walk, climb stairs, range of motion). Compare week-to-week progress to see if the supplement is helping. If pain worsens or new symptoms develop, stop and consult your doctor

This research describes findings from a single 28-day study and should not replace professional medical advice. Before starting astragalus extract or any supplement, consult with your healthcare provider, especially if you have existing medical conditions, take medications, are pregnant or breastfeeding, or have allergies. Astragalus may interact with certain medications, including blood thinners and immunosuppressants. If you experience severe knee pain, swelling, or inability to bear weight, seek immediate medical attention. This summary is for educational purposes only and does not constitute medical advice.