Safety

Proven safety profile 

Safety

ENTONOX, a ready-to-use gas mixture consisting of 50% nitrous oxide and 50% oxygen, has well-known and well-documented analgesic effects. It is extremely safe in a wide variety of clinical indications. A significant number of patients have been treated with few serious side effects or adverse events being reported (1, 2).

 

It has been used safely as an analgesic in the UK for the past forty years with few reported side-effects.

Are there any side-effects? 

The side-effects associated with the correct use of ENTONOX for short-term use are minimal and wear off quickly. Dizziness, euphoria and mild nausea are sometimes experienced but rapidly subside following withdrawal of the gas.

Contraindications 

The side-effects associated with the correct use of ENTONOX for short-term use are minimal and wear off quickly. Dizziness, euphoria and mild nausea are sometimes experienced but rapidly subside following withdrawal of the gas.

  • Gas trapped in a part of the body where its expansion may be dangerous, such as air lodged in an artery or artificial traumatic or spontaneous pneumothorax (collapsed lung).
  • Decompression sickness (the bends) or following a recent dive
  • Air encephelography
  • Severe bullous emphysema
  • Myringoplasty
  • Gross abdominal distension
  • Severe injuries to the face and jaw
  • Head injuries
  • If the patient has recently had any eye surgery where injections of gas have been used

Care is needed if the patient has suspected deficiencies in vitamin B12 or folic acid.

Little risk of overdosing 

There is almost no risk of overdose with ENTONOX. The fixed 50% nitrous oxide concentration, with a demand valve for self-administration, significantly reduces the risk of overdosing since the valve is operated by patient inhalation and closes when the patient ceases to inhale.

(1) Annequin D, Carbajal R, Chauvin P et al. Fixed 50% nitrous oxide mixtures for painful procedures: a French survey. Pediatrics 2000; 105(4):47-58.
(2) Gall O, Annequin D, Benoit G, et al. Adverse effects of premixed nitrous oxide and oxygen for procedural sedation in children. Lancet 2001; 358:1514-15.

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