If a diver reports a headache and red lips after a dive, what is a likely cause?

The symptoms of a headache and red lips after a dive are indicative of carbon monoxide poisoning. This occurs when a diver is exposed to carbon monoxide, which can be present in certain environments such as poorly maintained diving equipment or exposure to engines running in an enclosed area. Headaches are a common symptom of carbon monoxide exposure due to reduced oxygen transport capability of the blood, while red lips result from an increase in carboxyhemoglobin levels, which impacts oxygen delivery.

While nitrogen narcosis primarily affects cognitive function and can lead to impairments in motor skills, judgment, and perception due to the increased partial pressure of nitrogen, it does not typically present itself with symptoms like headaches or changes in skin coloration.

Decompression sickness, often referred to as "the bends," occurs due to nitrogen bubbles forming after rapid ascent and usually presents with joint pain, dizziness, or more severe neurological symptoms rather than the specific combination of symptoms described.

Oxygen toxicity manifests with symptoms like visual disturbances, twitching, and convulsions when exposed to high partial pressures of oxygen—instead of the headache and red lips observed here. Understanding the context and typical presentations of these conditions is crucial for diagnosing issues arising during or after dives correctly.