Read on to find the answers to your questions.
The airline you fly with needs to know that it is medically safe for you to fly. It isn’t mandatory to state this when booking a flight, but if you’re aware of any problems it’s best to let the airline know in advance – staff have the right to refuse boarding if you appear to be unwell at the time.
In general they may not let you fly if you have a condition that could get worse during a flight, or a contagious illness that can infect other passengers. In some cases you may be asked to provide a fit to fly certificate from your doctor.
While it may seem like extra paperwork, it’s important to remember these restrictions exist to keep everyone safe from a medical perspective.
Restrictions can vary between airlines, so it’s best to check if you have any specific concerns. Most will have a medical advisory service that you can find on the airline’s website.
Flying with certain conditions isn’t recommended, and some conditions that you should consult with your GP or specialist doctor about before flying. This usually applies to people with pre-existing medical conditions.
For example, if you have recently undergone heart surgery or have a worsening chest condition that affects your breathing, you may be deemed unstable to travel. The altitude and cabin pressure can cause a slight decrease in oxygen levels, which can cause problems for those with respiratory conditions. The lack of access to medical services may also be a concern for those with cardiac conditions or who recently had surgery.
You’ll also need to keep your medication safe in your cabin baggage. Read more about carrying medication abroad here. 
According to the Civil Aviation Authority, if you have a stable medical condition (e.g. asthma which is well controlled with medications) you don’t need a medical certificate.
If you have an unstable condition (e.g. asthma that isn’t well controlled and causes breathlessness on exertion) a note from your treating doctor outlining the medical condition will help with the decision on fitness to fly.
If you’re unsure if you need a fit to fly medical certificate for travel, speak to your GP or doctor if you answer yes to any of the below:
You can ask your GP – this usually means making an appointment to discuss the circumstances, and they may need to examine you.
This isn’t part of the NHS services that GPs provide, so you’ll need to pay a fee of around £30. The fee can vary between surgeries.
NHS GPs are extremely busy at the moment, so make sure to request your medical certificate at least a few weeks in advance.
If you can’t get an appointment with your NHS GP in time, you can also seek help from a private GP clinic.
To reduce the potential risk of passing on infections to others on board an aircraft, you should delay travel if you are feeling unwell, especially if you have a fever or have tested positive for COVID-19. An airline can deny boarding of any passenger who looks unwell, especially if they suspect the passenger might be infectious.
If you have recently recovered from an infectious disease, but are still showing physical signs of being unwell (e.g. crusted spots following chicken pox), you need to carry a letter from a GP confirming that you are no longer infectious.
Having a new cast can affect your circulation, so many airlines restrict flying during the first 24 or 48 hours after a cast has been fitted.
If you need to fly before then, the airline will usually ask for the cast to be split to avoid swelling during the flight. You can ask the fracture clinic team at the hospital to do this for you.
If you have your cast split before travelling, you may have to have the cast replaced once you reach your destination so it’s helpful to carry a letter confirming your medical details.
Having a perforated eardrum should not affect your fitness to fly.
Ear pain during flying occurs because of the change in air pressure in the cabin. A perforation actually allows air to move more freely than if it wasn’t perforated, so you’re unlikely to experience any problems.
If you’re well and your pregnancy has been straightforward and ‘low risk’, air travel is generally considered safe. But you should still check with your midwife or obstetrician before booking any flights.
Airlines request a medical certificate if travelling after 28 weeks of pregnancy. Most airlines won’t allow air travel after 36 weeks for a single pregnancy and 32 weeks for multiple pregnancies.
You also need travel insurance to cover both yourself and your unborn baby in the event you need to give birth unexpectedly during your trip.
Advice for flying after recent surgery varies between airlines and the type and extent of your surgery. Here’s when is typically safe to fly after surgery:
Most people with conditions such as asthma and chronic obstructive pulmonary disease (COPD) can fly safely. The cabin pressure during flight causes a slight reduction in oxygen levels, but this shouldn’t cause symptoms for those with a mild to moderate condition.
It’s a good idea to check the status of your condition with your doctor before you fly. If you need oxygen for the flight, you’ll need to notify the airline in advance and complete a medical information form. Your doctor will need to complete a section of it too.
Most people who have a stable heart condition (e.g. high blood pressure that’s well controlled with medication) can travel safely. If you need to travel with oxygen on board, you’ll need to let the airline know well in advance.
But, if your heart disease is severe, or your condition is deemed unstable, you may have to delay travelling until your condition has improved. The safest thing is to check with your GP or hospital specialist before you book your flight.
Most airports around the world offer assistance services if you have physical or hidden disabilities. You’ll need to arrange these in advance, so give yourself plenty of time to get in touch with the airline and airport.
If you need additional assistance during the flight be sure to mention this too. They will be able to make the necessary arrangements for any wheelchairs or medical equipment you may need.
It’s really important to have the right travel insurance in place if you have pre-existing medical conditions – just in case.