Slovakia's Tamara Potocka collapsed after her women's 200m individual medley heat at the Paris Olympics on Friday because she has asthma and did not have her inhaler with her, a team official said after the swimmer received medical treatment.

Medical staff rushed to assist Potocka and carried her away from the pool-side on a stretcher with an oxygen mask on her face after she finished seventh in the third heat of the event in the morning session at La Defense Arena.

The venue's media manager confirmed Potocka was conscious and under medical assessment.

"Tamara has asthma. This whole combination of nervous and physical tension while she did not have her inhaler immediately available to use contributed to the creation of this problem," Slovakia's team leader Ivana Lange said in a statement.

"She received oxygen and necessary medication, her condition is constantly monitored. A few minutes ago, the doctor told me that she must be monitored for several more hours."

The 21-year-old's time of two minutes 14.20 seconds ruled her out of advancing to the semifinals and was 4.3 seconds slower than the fastest swimmer, Canada's gold medal hope Summer McIntosh.