These answers have been put together by medical experts and Islamic scholars and researchers.
Should you fast if you have diabetes?
People with type 1 diabetes shouldn't usually fast, but people with type 2 diabetes on insulin should be able to. Their GP may advise adjusting the dose of their insulin, or their insulin type may need to be changed.
I get severe migraines when I don't eat and they get worse when I fast. Should I fast?
People with uncontrolled migraines should not fast. But managing your migraines is possible with the right medicine and certain lifestyle changes. Ask your GP for further advice on controlling your migraines.
Should you fast if you have high or low blood pressure?
People with well-controlled high blood pressure can fast. Your GP may advise you to change your medicine to help you take tablets outside fasting times. Someone with low blood pressure who is otherwise healthy may fast. They must ensure they drink enough fluid and have enough salt.
Can you fast if you're getting a blood transfusion in hospital?
No. Someone receiving a blood transfusion is advised not to fast on medical grounds. They may fast on the days when no transfusions are required.
I am on regular medication. Can I still fast?
Speak to your GP for advice on specific medicines.
Can you take tablets, have injections or use patches while fasting?
Taking tablets breaks the fast. But injections, patches, eardrops, and eyedrops don't break the fast as they're not considered to be food and drink - though there are differences of opinion among Muslim scholars on these issues. Islamic law says sick people shouldn't fast.
Is fasting harmful when a woman is expecting a baby? Must pregnant women fast?
There's medical evidence to show that fasting in pregnancy isn't a good idea. If a pregnant woman feels strong and healthy enough to fast, especially during the early part of the pregnancy, she may do so.
If she doesn't feel well enough to fast, Islamic law gives her clear permission not to, and to make up the missed fasts later. If she's unable to do this, she must perform fidyah, a method of compensation for a missed act of worship, such as paying for someone to be fed.
Does a breastfeeding woman have to fast?
No. Islamic law says a breastfeeding mother doesn't have to fast. Missed fasts must be compensated for by fasting at a later date, or fidyah, once breastfeeding has stopped.
Is Ramadan a good time to quit smoking?
Yes. Smoking is bad for your health and Ramadan is a great opportunity to change unhealthy habits, including smoking. To find your local service, visit the Smokefree website or ask your doctor or nurse to refer you to your local service.
You can also call the NHS Smokefree Helpline number on 0300 123 1044 (0300 123 1014 minicom) and ask to speak to an interpreter for the language you need. The helpline is open from 9am-8pm Monday to Friday, and from 11am-4pm on Saturday and Sunday.
Read more about stopping smoking.
From what age can children fast safely?
Children are required to fast when they reach puberty. It isn't harmful. Fasting for children under the age of seven or eight isn't advisable. It's a good idea to make children aware of what fasting involves and to practise fasting for a few hours at a time.
Can I use an asthma inhaler during Ramadan?
Muslim experts have differing opinions on this issue. Some say using an asthma inhaler isn't the same as eating or drinking and is therefore permitted during fasting. In their view, people with asthma can fast and use their inhalers whenever they need to.
But other scholars say the inhaler provides small amounts of liquid medicine to the lungs, so it breaks the fast. They say people with poor control of their asthma mustn't fast until good control is achieved.
Some people with asthma may opt for longer-acting inhalers so they can fast. See your GP for further advice.
Can I swim during fasting?
Yes, but don't drink the water. A bath or shower, or swimming, has no effect on the fast. No water should be swallowed during any of these activities, as that would break the fast.
Could dehydration become so bad that you have to break the fast?
Yes. You could become very dehydrated if you don't drink enough water before the fast. Poor hydration can be made worse by weather conditions and even everyday activities like walking to work or housework.
If you produce very little or no urine, feel disoriented and confused, or faint as a result of dehydration, you must stop fasting and have a drink of water or other fluid.
Islam doesn't require you to make yourself ill when you fast. If a fast is broken, it will need to be compensated for by fasting at a later date.
Can I fast while I have dialysis?
People on dialysis mustn't fast and should perform fidyah, such as paying for someone to be fed.
Article provided by NHS Choices