Beachgoers are being warned to watch out for swarms of bluebottle jellyfish after a dramatic rescue off the Raglan coast this week.
Emergency services including Waikato Westpac Rescue air ambulance, police search and rescue and St John rushed to the area on Monday when a 17-year-old went into anaphylactic shock after he was stung by a bluebottle.
The life-threatening reaction to the sting meant the teenager had to be winched off a boat near Gannet Island and taken to Waikato Hospital, where he was treated and discharged.
Raglan lifeguard patrol captain Chase Cahalane said bluebottles, also known as Portugese Man of War, had been an issue for beachgoers since January.
''On January 2 we treated more than 40 people for bluebottle stings and the reality is they can be extremely painful,'' he said.
The 25-year-old student paramedic said treatment of bluebottle stings was quite complex and it was important the stings were treated correctly to prevent more severe outcomes.
''First of all the tentacles from the sting area need to be removed carefully with rubber gloves or tweezers because if they are crushed it can release more venom into the wound area,'' he said.
After removing the sting patients are treated with the hottest water they can stand.
''The hot water neutralises the venom so it's important to make it really hot without burning the patient for about three or four minutes.''
Complicating the treatment is that heat promotes swelling which in turn leads to more pain but Mr Cahalane said it was a small price to pay for negating the effect of the sting.
After the hot water treatment the sting area can be iced for up to twenty minutes to reduce swelling.
Mr Calahane said bluebottles had been washing up to shore in swarms over the past couple of months.
''They are particularly bad in a south-west swell, they seem to come up in large groups and they can cause problems as people swim through them,'' he said.