CBD and tinnitus: what the research really says
On the question of cannabinoids and tinnitus, the state of the research is uncomfortable to summarise: there is practically no human data, and the most cited animal study concludes that there is no improvement, and possibly a worsening, of tinnitus-like behaviour. Mechanistic reasoning is not enough to fill that gap.
Contents
What tinnitus is, and why it resists
Tinnitus is the perception of a sound, a whistling, buzzing or ringing, with no external source. INSERM estimates that about 10 % of the adult population is affected, and that severely disabling forms account for fewer than 1 % of cases. The same dossier states that no curative option exists to date. A harmonised European survey was conducted in twelve countries among 11 427 adults and published in The Lancet Regional Health - Europe in 2022. It arrives at a prevalence of 14.7 % for tinnitus in general and 1.2 % for severe forms.
That absence of a curative option explains the intensity of demand, and the attention paid to any molecule presented as a lead. Recognised care today combines hearing aids where an associated hearing loss is present, sound therapies, cognitive behavioural therapy, and support for the distress attached to the symptom.
Why the endocannabinoid system comes up in this file
The argument encountered most often is mechanistic, and it rests on real facts. In the cochlear nucleus of the rat, a brainstem structure implicated in several models of how tinnitus arises, a large number of neurons carry CB1 cannabinoid receptors. A team at the University of Otago showed as early as 2007, in Hearing Research (Zheng et al.), that inducing tinnitus with salicylate alters that expression. The number of principal neurons expressing CB1 falls significantly in the ventral part of the nucleus, with no significant change in the dorsal part. The endocannabinoid system is therefore indeed present along the pathway.
A receptor present in a structure is not a demonstrated effect on a symptom. A great deal of content nevertheless stops at that stage and leaves the reader to fill the void. The rest of the literature does not go in the hoped-for direction.
What animal studies show: an unfavourable signal
The same team twice tested the step from mechanism to effect, and twice obtained the opposite of the expected result. In 2010, in Hearing Research, neither WIN55,212-2 nor CP55,940, two synthetic cannabinoid agonists, reduced tinnitus-related behaviour in a salicylate model. At the highest doses, both molecules significantly increased it.
In 2015, the experiment was repeated with acoustic trauma and a combination of Δ⁹-THC and CBD in a 1:1 ratio, at 1.5 mg per kilogram each. That mixture had been chosen to approximate the composition of an existing medicinal product. The title of the article, published in Frontiers in Neurology, sums up the result: "Cannabinoid CB1 Receptor Agonists Do Not Decrease, but may Increase Acoustic Trauma-Induced Tinnitus in Rats". The cannabinoids significantly increased the number of animals showing tinnitus in the group exposed to trauma, with no equivalent effect in the controls. The authors conclude that they could favour the perception of tinnitus where auditory damage already exists.
That protocol combined THC and CBD. It therefore does not allow the result to be attributed to cannabidiol alone, and isolated CBD has never been tested in a tinnitus model. Absence of data is not a favourable result. The same two authors also signed a 2019 overview in Current Opinion in Neurology, asking whether cannabinoid drugs would ease or exacerbate tinnitus. In it they judge that turning to the available cannabinoids for tinnitus is premature and unsupported by the data.
What is known in humans: almost nothing
No clinical trial has assessed cannabidiol against placebo in tinnitus. The ClinicalTrials.gov registry lists no study crossing cannabidiol and tinnitus. The only trial ever registered on cannabis in this indication, opened by an Israeli hospital, was withdrawn without having enrolled a single participant.
Demand from patients is nevertheless strong. A survey published in 2023 in the Journal of Otolaryngology - Head & Neck Surgery (Mavedatnia et al.) among 45 patients with tinnitus reports that 96 % of them would consider a course of cannabis and that 36 % had already used it.
This lack of data explains why no health authority recognises any cannabinoid as care for tinnitus. The same pattern is found elsewhere. Our review of what the clinical studies on CBD really say sets out why sample sizes and protocol durations limit the reach of most published work.
What the French framework says
In France, no CBD product may claim an effect on tinnitus, nor on any condition. Such a claim would tip the product into the category of medicinal products, with the authorisation obligations that go with it. New tinnitus, one-sided, pulsatile or accompanied by sudden hearing loss, calls for prompt advice from a healthcare professional.
In our place as a seller, we can publish what our products contain. Every batch is analysed by an independent laboratory and the certificate can be consulted before purchase. On documented adverse effects and the interactions worth knowing, our dedicated page on CBD side effects gathers the available data. The neighbouring question of headaches is covered in CBD and migraine.
Frequently asked questions
Can CBD make tinnitus disappear?
Nothing in the available literature supports saying so. No randomised clinical trial has tested cannabidiol alone in this indication, and the main animal work concludes that there is no improvement. INSERM also states that no curative option for tinnitus exists to date.
Can CBD make tinnitus worse?
Two experiments at the University of Otago observed an increase in tinnitus-like behaviour, above all where auditory damage was already present. The first, in 2010, involved synthetic agonists, the second, in 2015, a THC and CBD mixture. These protocols do not allow the role of CBD to be isolated, and transposition to humans is not established. The signal is nonetheless worth knowing about.
Why are there so many positive testimonials online?
Because a fluctuating symptom, highly sensitive to attention and to stress levels, lends itself particularly well to placebo effects and to selection bias: people who were disappointed report back less often. That is the whole point of placebo-controlled trials, which are missing here.
Who should be consulted about troublesome tinnitus?
A doctor, in the first instance a general practitioner who can refer on to an ENT specialist. A hearing assessment identifies any associated hearing loss, which is often central to care. No wellbeing product replaces that step.
Written by the Phytogrammes team
Every article in this journal draws on primary sources (ANSM, EFSA, EUR-Lex, peer-reviewed publications) and on the lab's own practice: batch-by-batch HPLC analyses, measured cannabinoid profiles. Our approach.
Article published on . CBD is not a medicine.