A “Prescription” refers to the written permission of a medical practitioner that will authorise a patient to be issued with a medicine or treatment, e.g. a pain-killing drug or some physiotherapy.

A “Referral” is not a prescription; a referral is made by a practitioner to a specialist, or specialist unit, when they themselves are unable to conduct certain required examinations, tests and sometimes treatment, due to lack of qualification, experience or resources.

Other Definitions

Medication – treatment with one or more medicines.

Medicine – any pharmaceutical preparation, prescribed or over-the-counter, used in medication.

Pharmaca – the active biological ingredient of a medicine.

Drug – any substance, illicit or legal, used for non-medical purposes.

Relevance to Aviation Safety

Many aviation workers such as pilots, air traffic controllers, maintenance technicians and cabin crew will be involved with safety critical operations. Such operations and activities require adequate vigilanceattention, focus, motivationinformation processing capability, judgement, coordination, stamina and physical strength.

Illnesses and conditions that might seem minor in many walks of life can have a profound impact on the safe operation of aircraft. Similarly many medicines prescribed, or over-the-counter, used to treat such illnesses may themselves introduce side-effects that also impact on flight safety. For example: for a pilot, operating at altitude, the common cold can cause loss of balance references and even severe trauma, as well as loss of concentration and tiredness. Similarly, using an antihistamine to treat an allergy can also induce tiredness, confusion, dizziness and blurred vision.

Preventative Medicines

Medicines are frequently used in a preventive capacity e.g. anti-malarial agents, hepatitis vaccines, anti-diarrhoea, and antibiotics. This use is to avoid, or resist, illnesses and symptoms that can negatively affect flight safety; however, the side-effects of such preventive medication itself must also be considered.

Not all preventative medicines, in all countries, need to be prescribed.


Some aviation workers, such as pilots and air traffic controllers, have to maintain a “Medical Category” to maintain the privileges given through a “licence”. Such medical categories need to be issued by approved practitioners, and/or through approved medical centres.

Medical examinations are periodic e.g. annually or biannually; therefore, during the working year aviation employees will become ill and consult their family doctors who are not necessarily aeromedical specialists, and it is these doctors who will issue prescriptions. This places the responsibility onto aviation workers to assess their own ability to operate safely, both whilst ill and whilst being treated.

The flight safety aspects of medication involve an assessment of risk. Some disorders are minor and treatment may be more detrimental to flight safety than the disorder itself. On the other hand, more serious illnesses might not be acceptable without adequate treatment. Some diseases have such potentially adverse effects on flight safety that, whether treated or not, the diagnosis is disqualifying. However, as medical science advances, diseases in this latter group are becoming less frequent, as are the performance limiting side-effects of medicines.

Often the requirements of holding a licence include the need to inform a qualified medical examiner, and also the employer, of any illness and consequent medical treatment; especially if the worker considers that it may affect their performance.

In considering whether a licence holder should continue to exercise licence privileges while on medication, at least the following questions should be asked[1]:

  • Is the illness and its symptoms for which medication is prescribed disqualifying?
  • What are the usual and expected impacts of the pharmaca, are they likely to endanger flight safety and, if so, what is the duration of these effects?
  • What are the possible side-effects, and their duration, of the medication?

Particular attention needs to be paid to impacts and side-effects on the following areas:

  • central nervous system,
  • autonomic nervous system,
  • senses, and
  • organs.

To support workers in fulfilling their responsibilities and to ensure adequate supervision, employers need to provide education and support resources. Information on medicines and their effects, in relation to aviation, can be found in the ICAO Manual of Aviation Medicine[1].

With adequate support and supervision it is possible for pilots and air traffic controllers etc. to continue working safely, even in critical areas. For example, in some countries it is acceptable for pilots to fly with illnesses such as depression, whilst taking psychoactive medicines that affect cognitive abilities, provided a suitable supervisory programme is maintained.

Self Medication and Treatment

It must be recognised that because some illnesses may impact on a worker’s employment (money earning potential or even career) some workers will be tempted to self-medicate and self-treat without informing their aeromedical examiner or employer. It is possible for aviation workers to access medicines “over the counter”, without prescription, legally or illegally, and therefore retain some secrecy if they wish.

Many medicines, herbal treatments and psychoactive drugs are available over the counter. The levels of supply and access to medicines and drugs are not uniform worldwide, and nor is their classification as legal, illegal or prescription only. The internet has opened up cross-border markets and also many aviation workers can travel to countries where controls and classification differ from their home country.

In many cultures so-called alternative, traditional and herbal remedies are considered harmless, and these treatments are often used in parallel with prescribed medicine. Use of herbal medication, traditional and alternative treatments require particular attention to possible side-effects and their interactions with prescribed medicines and treatments.

Self-treatment also extends to the “over-dosing” of prescription medicines, where a patient decides that a higher dose is required to gain the necessary affect. This may be common with sleeping pills and antipsychotic medicines. It also extends to the supplementing of prescribed medication with so-called recreational drugs, e.g. sleeping pills and alcohol, or analgesics and marijuana.

It may also be considered as self-treatment when a patient ceases to complete a course of prescribed medicine or treatment without consulting his/her physician. The consequences may have an impact on safety, and the health of the patient.


Any medicine, treatment, drug, herbal remedy or traditional cure, that is likely to significantly interfere with the primary senses, perception, cognition, alertness, coordination, judgement, etc., should be prohibited for all safety-critical personnel. Any other medicine and treatment etc., which may interfere with the same should be supervised. This requires workers to self-report both illnesses and medication, including any self treatment and use of drugs. Employers need to strike a balance between protecting flight safety and promoting a reporting culture that encourages employees to admit to the medical problems they have, and to inform about the medicines they are taking. This requires continual and creative education and awareness-raising.

Employers can achieve an effective balance by clearly defining their policy on health, medication, alcohol and other drugs. For such policies to be effective, the employer will need to provide suitable support (resources and procedures), to encourage self-reporting. Within any policy clear lines need to be defined between the consequences of unacceptable behaviour (e.g. concerning use of recreational drugs and alcohol at work) and how employees who self-medicate, but then “declare”, will be supported.

Educational and awareness resources need to be directed at discouraging self-medication and the use of alcohol and other drugs, as well as the benefits of seeking immediate professional medical help for uncertain symptoms, and the need to adhere to programmes of prescribed medicine and treatment, under supervision.

Detailed information on problematic use of psychoactive substances in the aviation workplace can be found in ICAO Doc 9654[2].

Further Reading


  1. a b c ICAO. 2012. Manual of Aviation Medicine. 3rd Edition. Doc 8984 AN/895.
  2. ^ ICAO. 1995. Manual on prevention of problematic use of substances in the aviation workplace. Doc 9654.

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