Serotonin syndrome (SS) is a toxic state characterized by increased serotonin activity. It has been suggested that severe serotonin syndrome usually involves monoaminoxidase inhibitors (MAOIs).

To quantify in how far severe SS is associated with MAOIs.

Systematic review and quantitative analysis of all SS cases published between 1 January 2004 and 31 December 2014. Severe SS was defined as cases, either requiring intensive care or resulting in death. Cases were included if they met the diagnostic criteria for SS according to at least one of the three diagnostic criteria systems (Hunter, Radomski and Sternbach).

Of the 299 included cases, 118 (39%) met the definition for severe SS. Eight cases had insufficient information to enable severity classification. Of the severe cases, 48 (40%) involved a MAOI. Of these, 67% related to psychiatric MAOIs, such as phenelzine and moclobemide and 33% to a somatic MAOI, such as methylene blue and linezolid. Of the remaining 173 non-severe SS cases, 24 cases (13%) involved a MAOI. In these, 12% related to a psychiatric MAOI and 83% to a somatic MAOI. One case (4%) had a combination of both. The odds ratio for MAOI involvement in severe versus non-severe serotonin syndrome was 4.3 (CI 2.4 – 7.5; p < 0.001).

In the majority of published case reports, drugs other than MAOIs are involved in serotonin syndrome, even in severe cases. MAOIs are, however, more common in severe serotonin syndrome than in non-severe cases.

M. Ott: scientific advisory board member of Astra Zeneca, Sweden. U. Werneke: received funding for educational activities on behalf of Norrbotten Region; Astra Zeneca, Eli Lilly, Janssen, Novartis, Otsuka/Lundbeck, Servier, Shire, Sunovion. Others: None

Serotonin and sympathomimetic toxicity (SST) after ingestion of amphetamine-based drugs can lead to severe morbidity and death. There have been evaluations of the safety and efficacy of on-site treatment protocols for SST at music festivals.

The study aimed to examine the safety and efficacy of treating patients with SST on-site at a music festival using a protocol adapted from hospital-based treatment of SST.

The study is an audit of presentations with SST over a one-year period. The primary outcome was need for ambulance transport to hospital. The threshold for safety was prospectively defined as less than 10% of patients requiring ambulance transport to hospital.

The protocol suggested patients be treated with a combination of benzodiazepines; cold intravenous (IV) fluid; specific therapies (cyproheptadine, chlorpromazine, and clonidine); rapid sequence intubation; and cooling with ice, misted water, and convection techniques.

One patient of 13 (7.7%) patients with mild or moderate SST required ambulance transport to hospital. Two of seven further patients with severe SST required transport to hospital.

On-site treatment may be a safe, efficacious, and efficient alternative to urgent transport to hospital for patients with mild and moderate SST. The keys to success of the protocol tested included inclusive and clear education of staff at all levels of the organization, robust referral pathways to senior clinical staff, and the rapid delivery of therapies aimed at rapidly lowering body temperature. Further collaborative research is required to define the optimal approach to patients with SST at music festivals.