A pharmacist in Dublin has been praised for administering two life-saving adrenaline injections to a teenager who was going into anaphylactic shock.

The incident happened on Grafton Street in Dublin on Tuesday evening. A 17-year-old female with a known severe nut allergy became ill after consuming a chocolate drink she had purchased earlier.

The teenager rang her father, who told her to go to the nearest pharmacy. She entered a Hickey's Pharmacy, where she was evaluated by pharmacist, Sarah Chambers.

"The patient explained that the last time she had an allergic reaction to nuts was when she was aged four. She displayed characteristic symptoms of anaphylactic shock including a rash and swollen lips and so we immediately called an ambulance. I then administered two adrenaline pens and stayed with her to monitor her condition until the ambulance arrived," Ms Chambers explained.

The young woman was rushed to St James's Hospital, where she was later discharged having made a full recovery.

Anaphylactic shock, or anaphylaxis, is a severe allergic reaction, which is caused by the body's immune system over-reacting to the presence of a foreign body. Common causes are peanuts, shellfish, eggs and wasp/bee stings.

Symptoms can include a swelling of the mouth and throat, difficulty swallowing or speaking, difficulty breathing, hives on the body, nausea and sudden weakness.

"Adrenaline is a first-line treatment for anaphylaxis. It works by constricting the blood vessels to increase blood pressure, relaxes muscles in the lungs to reduce wheezing, improves breathing and stimulates the heart rate. It also works to reduce hives and swelling that may occur around the face and lips," Ms Chambers said.

The Epi-pen is designed for anaphylactic emergencies. It provides an immediate dose of adrenaline and can be administered in emergency situations by trained pharmacists. The ability to administer the Epi-pen in first response situations such as this was made legal by the then-Minister for Health, Leo Varadkar, in October 2015.

Anyone who suspects they may have an allergy should consult their GP or pharmacist immediately. Meanwhile, those with known severe allergies are reminded to always carry two in-date adrenaline pens.