Irritability can be a challenging symptom, often present in a wide range of different clinical settings. Unipolar depression can present with irritable mood, as can the manic states of bipolar disorder. Irritability is also a common problem in borderline personality disorder, as well as in various other populations, such as in those with autism, dementias, brain injury, conduct or oppositional disorders, and addiction disorders. In some cases, arguably, irritability could be considered the primary problem for some people, which either exists on its own as a solitary symptom, or is the direct single cause of the person's other life problems (e.g. in relationships, employment, conflicts with the law, ability to work or study, etc.)
A variety of simple factors usually make irritability worse:
1) sleep problems. Insomnia or deliberate reduction of sleep hours will magnify irritability.
2) hunger. For some individuals especially, allowing a hungry state without eating healthily will magnify irritability.
In both cases above, a vicious cycle can arise, as greater irritability may prevent sleep or cause a further lack of appetite.
3) multiple environmental or medical irritants which are not improving: for example, crowding, noise, poor air quality, physical pains or discomforts
Therefore, in approaching irritability, it is essential to take steps to improve sleep, nutrition, pain, and environmental stimuli.
Further therapy for irritability should of course involve healthy lifestyle practices, such as exercise, relaxation, and meditative activity (if not formal "meditation" then something which accomplishes something similar, such as music listening or performance, biofeedback, hot baths, massage, etc.) Reduction of caffeine intake, etc. could be important to try. Developing healthy philosophical practices can be very useful; for example, some type of calm or peace-oriented religious or other community involvement may add to one`s ability to manage irritability, especially since there could be group-based support and healthy cultural activities.
Pharmacological treatment of irritability, if necessary, would depend on obvious underlying causes. In substance withdrawal states, for example, temporary appropriate sedation (e.g. with benzodiazepines, clonidine, or anticonvulsants such as gabapentin) could ease the irritability. In manic states, mood stabilizers, antipsychotics, and benzodiazepines which ease the manic symptoms, would be expected to ease the irritability. In major depression, an antidepressant of any sort, if it works for the individual, could dramatically improve the irritability. ADHD can be a cause of irritability, which--seemingly paradoxically--could improve with stimulant therapy.
In this post, I am particularly interested in looking at specific pharmacological treatments for idiopathic irritability, or irritability which has existed as a long-term emotional dynamic such as in those with borderline personality traits or disorder.
Here are a few pertinent links to abstracts in the research literature:
this 12 week randomized study shows modest benefits from divalproex to treat irritability in autistic children (ages 5-17)
http://www.ncbi.nlm.nih.gov/pubmed/18273430 gabapentin useful for borderline patients over a 6 month period
http://www.ncbi.nlm.nih.gov/pubmed/19283647 (this is a good article, but it's in German)-- review of anticonvulsant effectiveness in personality disorders. There is evidence in this paper to support trials of valproate, topiramate, and possibility also lamotrigine. They describe some data on carbamazepine as well. The level of evidence is such that I think these medications could be worth trying cautiously on an individual basis, particularly to target symptom domains such as irritability. However, I think expectations should be modest, due to there most likely being a lot of variability in an individual's response.
I am interested in the use of clonidine for irritability. This drug is effective for treating withdrawal states (including one of the most unbearable withdrawal states possible, from opiates), but has also been used for many years to treat ADHD. It can help with tic disorders as well, so could be a good choice for managing ADHD + tic comorbidity, a difficult problem often made worse by stimulants. Clonidine was originally developed as a treatment for high blood pressure. My main concern about clonidine is about how well its effects persist if taken continuously for more than a few months. Here is an article about treating borderline personality patients with clonidine:
Here's a study looking at treating children with conduct or oppositional problems with stimulants and/or clonidine: http://www.ncbi.nlm.nih.gov/pubmed/10660814
In conclusion, there are various options to try in the treatment of irritability from most causes. While the evidence base is limited, there is support for attempting a variety of different pharmacological treatments for idiopathic irritability, particularly anticonvulsant medications.