Could Botox be used to treat severe asthma?

Behind the Headlines

Tuesday March 25 2014

Botox can cause a localised temporary paralysis

Botox – not just for wrinkles

“Botox is commonly used to smooth out wrinkles, but new research suggests it could be used to help asthma sufferers,” the Mail Online reports.

While early results seem encouraging, the research being reported on is still at proof of concept stage.

For most people, asthma can be controlled using conventional treatments such as inhalers. However, some people's asthma symptoms are resistant to treatment (intractable).

The researchers make the case that abnormal vocal cord movement, caused by muscle spasms, may be responsible for some of these intractable asthma cases.

So they tested Botox (botulinum toxin) – a powerful neurotoxin that can cause temporary partial paralysis – on 11 people with severe intractable asthma who had abnormal vocal cord movements that had failed to respond to speech therapy.

After injecting a course of Botox into their vocal cords, participants reported better asthma control, and airway size at the level of the vocal cords was increased. However, there were no changes in measures of lung function.

While the results seem promising it is important to point out that there was no control group in this small study. So any improvement in symptoms could be due to the placebo effect.

As the treatment appears to be relatively safe it should lead to further randomised controlled trials, which will help assess whether a placebo effect influenced the results.


Botox  handle with care

Botox, aka botulinum toxin, is only safe in minute doses. Above a certain level it is extremely deadly.


It is estimated that a teaspoon of botulinum toxin is enough to kill the entire population of India (1.2 billion people).

Where did the story come from?

The study was carried out by researchers from Monash University in Australia. It was funded by Monash Medical Centre. 

The study was published in the peer-reviewed journal Respirology.

The results of this study were poorly reported by the Mail Online. The story headline read “injections into the vocal cords proven to help patients breathe”. Although the study did find that people reported better asthma control, there were no improvements in lung function after the treatment.

In addition, as the study was not a randomised controlled trial, it cannot prove that the improvements in asthma control were due to the injections.

Finally, the article appears to have been “cut in half” as it has no proper ending and just peters out.


What kind of research was this?

This study was a case-series of 11 people who still had severe asthma symptoms despite optimised treatment and who had abnormal vocal cord movement which was not improved by speech therapy.

All 11 were treated with vocal cord injections of Botox. The researchers wanted to see whether Botox is an effective treatment that improves asthma control.

A small study like this, often referred to as a phase I trial, can provide some indication of whether Botox may be a safe and effective treatment. However a randomised controlled trial is required to determine whether any improvements seen are actually due to the treatment and are not just due to people reporting improved symptoms because they have been treated (the placebo effect).


What did the research involve?

The study involved 11 people who had severe asthma symptoms despite optimised treatment and who had abnormal vocal cord movement which was not improved by speech therapy. They were treated with Botox injections into one of their vocal cords. If people didn’t have improved symptoms they were given additional injections.

After treatment, response was assessed using the following:

  • asthma control test scores – a self-reported “scorecard” that is based on the severity and frequency of symptoms (minimum five points for poor control, maximum 25 points for good control)
  • spirometry (where the amount and/or speed of air that can be inhaled or exhaled is measured)
  • measuring vocal cord narrowing using computerised tomography (CT) scans, where a series of X-rays are taken to create a detailed image of the larynx

The researchers also collected information on any side-effects that were experienced by the participants.


What were the basic results?

Four people had a single Botox injection, and the other seven received repeat injections, with two people receiving four injections. In total, 24 injections were given.

Asthma control test scores one month after each injection were significantly improved, from an average of 9.1 before treatment to 13.5 after treatment. The researchers state that changes of three or more on this score are clinically important.

Airway size was measured by computerised tomography in 10 patients. Some patients had received multiple injections when it was measured. Compared to before treatment, the amount of time the airway was narrowed below the lower limit of normal significantly improved from 39.4% to 17.6%.

There was no change in lung function as assessed by spirometry.

Side effects were noted after 17 of the 24 injections. Dysphonia (voice disorder) occurred after 16 injections and lasted for up to six weeks in five of the cases, though they were still able to have normal conversations. Dysphagia (difficulty swallowing) was reported after six of the 24 injections. All cases were categorised as ‘mild’.

One person with severe asthma required hospital admission and steroids after having the injection under general anaesthetic. The study fails to make clear whether this was due to an adverse reaction to the Botox or to the general anaesthetic (or to something else entirely).


How did the researchers interpret the results?

The researchers conclude that “although a placebo effect cannot be ruled out, local injection of botulinum toxin may be an effective treatment for intractable asthma associated with abnormal vocal cord movement. Further mechanistic studies and a double-blind randomised controlled trial of botulinum toxin treatment are merited.”



This small study involved 11 people who had severe asthma symptoms despite optimised treatment and who had abnormal vocal cord movement which was not improved by speech therapy. The results suggest that Botox injections into one of the vocal cords improved asthma control and the airway size at the level of the vocal cords was increased. However, there were no changes in measures of lung function.

As the researchers point out, this study was not controlled or blinded and a placebo effect cannot be excluded.

It is also not known how long any effect would last, as participants were only assessed for one to three months after treatment.

It is also currently unclear how common the problem of abnormal vocal cord movements is in people with poorly controlled asthma.

In conclusion, although Botox could be a promising treatment for people with asthma who also have abnormal vocal cord movement, further randomised controlled trials are needed.

If you do feel that your asthma symptoms are poorly controlled then speak to your GP or the doctor in charge of your care. There are a range of treatments that may be of benefit.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.

Analysis by Bazian

Edited by NHS Choices

Links to the headlines

Could BOTOX be used to treat asthma? Injections into the vocal cords proven to help patients breathe. Mail Online, March 24 2014

Links to the science

Baxter M, Uddin N, Raghav S, et al. Abnormal vocal cord movement treated with botulinum toxin in patients with asthma resistant to optimised management. Respirology. Published online March 23 2014


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Next review due: 14/07/2017

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