Flying and Health — Page 116, Lesson 184

I want to walk you through a critical section on flying and health — specifically, the hazards of common drugs and medications in an aviation context. The key point I want you to take away from the start is that the precautionary advice printed on medicine packaging does not account for the unique problems of reduced performance associated with flying. So what might be a safe dose for someone on the ground can be dangerous for a pilot in the air. Let's go through the drug groups one by one, because each has a specific mechanism and a specific hazard. First, cold, hay fever, and influenza cures. Many of these contain antihistamines, often in a slow release form. Antihistamines cause drowsiness and dizziness. The drowsiness is particularly hazardous because the individual may not recognise it — and it can recur after a period of alertness. So you might feel fine for a while, then suddenly feel drowsy again. Next, anti-spasmodic drugs are often included in these compounds. They can cause visual disturbances. Also, quinine can be present, which can adversely affect hearing and cause dizziness. Allergy treatments — most of these contain antihistamines, so the same drowsiness and dizziness warnings apply. Nasal decongestants, whether in drop or inhaler form, contain stimulants. So they don't make you drowsy — they do the opposite — but stimulants bring their own problems, as we'll see. Antacids are interesting. They contain atropine, which causes visual problems, and also sodium bicarbonate, which liberates carbon dioxide in the stomach. At altitude, that carbon dioxide can cause acute stomach pain due to barotrauma — the gas expands as pressure drops, and there's no easy exit from the small intestine, as you can see in the diagram of the gastro-intestinal tract . Diarrhoea controllers contain opiates, which cause both nausea and depression. Weight controllers — most contain stimulants such as benzedrine or dexedrine. These cause wakefulness, but also nervousness and impaired judgement. So the pilot may feel alert but actually be making poor decisions. Now, stimulants and tranquillisers — I'll group these together because the list of effects is the same for both categories. They can cause: sleepiness, nausea, depression, visual disturbances, mental disturbances, intolerance to alcohol, impaired mental and physical activity, impaired judgement, and dizziness. That's a long list, and every single one of those is a threat to flight safety. Aspirin — excessive intake can cause gastric bleeding. Now, a very important general warning: mixing drugs or medicines is particularly dangerous. If two are taken at the same time, it may render both more potent, or cause side effects not experienced with each individual medicine alone. So even if two drugs are safe separately, together they can be unpredictable. Finally, let's talk about anaesthetics and analgesics. Following local and general dental and other anaesthetics, a period of time must elapse before air crew return to flying. The period varies considerably from individual to individual, but the minimum standards are: at least 12 hours after a local anaesthetic, and 48 hours following a general anaesthetic. These are not recommendations — they are the minimum safe intervals before you can consider yourself fit to fly.