Which clinical trials tested ginkgo biloba for tinnitus and what were their results?

1. Big trials first: the 2001 BMJ multicentre trial that reshaped opinion

A large double‑blind, placebo‑controlled trial published in BMJ enrolled 1,121 adults with stable tinnitus and used a standardized Ginkgo extract (LI 1370); investigators matched 978 participants into pairs and collected outcomes by postal questionnaire, concluding that the extract did not show convincing benefit for the broad study population ^[1]. That trial set the bar for sample size and raised skepticism because it failed to demonstrate clinically meaningful improvement at the population level ^[1].

2. EGb 761® studies: a cluster of positive randomized trials

A group of randomized, placebo‑controlled trials using the specific standardized extract EGb 761® consistently reported superiority of active treatment over placebo in pooled summaries and in the trials reviewed by Heder and colleagues; a systematic review argued that all eight randomized, placebo‑controlled EGb 761® trials showed statistically significant superiority of EGb 761® ^[2]. Subsequent single trials and combinations (EGb 761® versus pentoxifylline; EGb 761® plus hearing aids) have reported improvements in tinnitus measures, including one randomized comparison with pentoxifylline and a small Brazilian randomized study reporting benefit when EGb 761® was used with hearing aids ^{[6] [7]}.

3. Systematic reviews and Cochrane: uncertainty and probable lack of effect

Major evidence syntheses reached different conclusions. A Cochrane review and later systematic assessments concluded the evidence does not demonstrate clear benefit and that Ginkgo biloba probably does not decrease tinnitus severity or improve quality of life overall ^{[5] [4]}. Some meta‑analyses that pooled heterogeneous products found no benefit and cautioned that positive findings often depended on restricting analysis to EGb 761® only ^{[2] [4]}.

4. Heterogeneity of products and trials drives disagreement

A central reason for divergent conclusions is product heterogeneity: trials used different Ginkgo preparations (EGb 761®, LI 1370, and others) with different doses and quality control, and some reviews pooled dissimilar products, biasing results toward null or mixed findings ^{[2] [1]}. Reviews and recent papers explicitly note that non‑EGb 761® trials generally failed to show benefit, while EGb 761® trials more often reported positive outcomes ^{[3] [2]}.

5. Recent and ongoing trials: renewed interest but not settled science

Clinical research continues: registered and recent trials (for example, EGb 761 trials registered and completed or ongoing in the 2020s) aim to re‑test EGb 761® in narrower patient groups and different combinations ^{[8] [9]}. A 2019–2020 small randomized study in Brazil reported improved self‑perception scores after 90 days with EGb 761® alone or combined with hearing aids, but sample sizes were small (n=33 total) and limits on generalizability remain ^[7].

6. Guidelines and safety: professional bodies advise caution

European and American tinnitus guidelines advise against using Ginkgo biloba for tinnitus because systematic reviews have not shown proven efficacy and there are potential harms — notably bleeding risk from interactions with antithrombotic drugs — so clinicians are warned to avoid routine recommendation ^[10]. Reviews emphasize potential harms alongside uncertain benefit ^{[10] [5]}.

7. How to read the evidence: what matters for patients and clinicians

Available sources show the strongest positive signals come from trials using one standardized extract, EGb 761®, but overall syntheses (Cochrane and later systematic reviews) find uncertainty or probable lack of clinically meaningful benefit when considering all trials and products ^{[2] [4] [5]}. The literature repeatedly warns that pooling different extracts masks heterogeneity and that subgroup effects (e.g., in dementia patients with tinnitus) have been reported but are not definitive (p1_s1, ^[11] — note: sources mention subgroups but broader evidence syntheses still conclude uncertainty) ^{[2] [11]}.

8. Bottom line and reporting gaps

The available reporting documents a clear split: several randomized trials of EGb 761® report statistical benefit ^{[2] [6]}, while large trials using other standardized extracts and pooled reviews conclude no reliable benefit for tinnitus overall ^{[1] [4] [5]}. Available sources do not mention long‑term harms beyond bleeding risk in detail or definitive biomarkers that predict who might respond; further large, product‑specific randomized trials with consistent outcome measures would be required to resolve the disagreement ^{[10] [5]}.