Seven cases of E.coli O157 are being investigated by the Public Health Protection Unit of NHS Greater Glasgow and Clyde (NHSGGC), all of which were thought to be contracted at the arena.
The cases could being linked to burgers sold at food outlets inside the £125million arena, although other food items are also being considered.
The period of time under investigation - January 17 to 25 - saw the Hydro holding a series of five events by Top Gear, on Friday 17 to Sunday 19.
Also on at the venue in that period was a gig by Del Amitri, on Friday, January 24, and an event as part of the Celtic Connections Festival on Saturday, January 25.
The venue holds up to 12,000, meaning up to 84000 people attended the Hydro in that period.
NHSGGC is liaising with Health Protection Scotland, the Food Standards Agency and Glasgow City Council in its investigation.
All seven people affected are recovering at home.
One of the cases is from the NHSGGC area, two are from the NHS Lanarkshire area, three from NHS Lothian and one is from Cumbria.
Dr Gillian Penrice, consultant in Public Health Medicine at NHSGGC, said: "Investigations are under way to identify if there is any common source.
"While there is no conclusive evidence our initial investigations have indicated that there may be a link to the consumption of burgers at the SSE Hydro and Glasgow City Council Environmental Health Officers are working closely with the vendors to ensure all appropriate food hygiene standards are being met.
"I would ask anyone who has attended the Hydro recently and who has experienced or is continuing to experience symptoms including stomach cramps, diarrhoea, nausea and fever to contact their GP."
A spokesperson for the Hydro said: "We have been contacted by the Environmental Health in relation to an investigation into an e-coli outbreak which they believe may have been connected to one of the catering outlets on our premises.
"We are awaiting further details to establish the exact cause of this isolated incident and our catering partners have been working closely with environmental health officers.
"The initial review of our caterers standard procedures have been found to be satisfactory and EHO have seen nothing in their processes and practices which concerns them.
"We wish to assure the public that at this time we have no significant concerns in relation to catering for our patrons."