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Sweat test

A sweat test is used to confirm a diagnosis of cystic fibrosis in children.

Sweat testing is a safe procedure but can cause some mild discomfort because the child’s skin heats up over a small area during the test. There is a very slight risk of causing a tiny, superficial burn to the skin. Young babies less than 6 weeks old are most affected. However, thousands of children have received this test without any problem.

Most individuals will exhibit a sensitivity to pilocarpine, which will show as mild redness or rash on the skin at the site of the electrodes. This will usually disappear within 2–3 hours, with no after-effect. On rare occasions we cannot collect enough sweat for the test, for instance, in very small babies. If this happens, we will repeat the test at a later date.

Collecting the sample

Sweat is collected by applying a very small electrical current to your child’s skin (usually on their arm or leg) along with a chemical called pilocarpine that helps to cause sweating.

The sweat test usually takes about one hour; however, it may be necessary to repeat the test if insufficient sweat is collected. It is important the child remain still throughout the test.

Contact your preferred collection centre or your referring doctor if you have any questions about undertaking a sweat test.

Where can my child have a sweat test?

Sweat tests are a specialised test. You will need to make an appointment at one of the following collection centres:

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QIS document number: 27625

Last updated: 15 December 2021