Complications may include: the patient being allergic to the anaesthetic, the dose given may be too high, or the anaesthetic effect has taken effect faster than wanted. Where complications occur, it is generally in connection with general anaesthesia.

Airway obstruction:
Irritation to the breathing passages causing spasms and interfering with breathing.

Incomplete reversal:
Inability of the muscle relaxant to wear off properly by the time that the patient has woken up. The patient is aware, but paralysed, this is easy to detect and breathing can be assisted.

Nerve damage:
Some local anaesthetics can cause long term nerve damage, while some general anaesthetics can inflict brain damage. Brain damage will also result from depressed blood circulation.

Malignant hyperthermia:
An uncommon severe reaction to a general anaesthetic that results in extremely high body temperatures, blood pressure and heart rate. This rare reaction has a tendency to run in families.

Awareness:
A much talked about, but in fact a very rare, occurrence. This happens in only one percent of all surgeries involving a general anaesthetic. It means that the patient appears asleep, but is not fully unconscious. This only happens when muscle relaxants are given. The patient cannot talk, move or speak. Newer technology can help an anaesthetist to reliably monitor for signs that this is happening.

Complications of Epidural and Spinal Blocks:

• decrease in blood pressure
• having to remain still for administration (very difficult when in labour)
• problems in bladder emptying
• backache
• more serious complications are rare, but include convulsions, infection and death.