Hot weather

Cystic fibrosis affects the balance of salt in your cells. Sweating more when it’s hot can cause you to lose a lot of salt. This can increase your likelihood of becoming dehydrated and of developing low salt levels, known as hyponatremia. Being dehydrated can cause mucus to thicken, making symptoms of your CF worse. 

Dehydration or having low salt levels can also be dangerous but they are simple to prevent when you know how:

Drink often

You might not always feel thirsty but make sure you keep up your fluids. You can sip on water or your preferred drink throughout the day. Tea and coffee are not as hydrating as other drinks so make sure you do not rely on these alone. Try to eat fruits that have a high water content such as watermelon, tomatoes or cucumber.

Snack on salty foods or take your salt tablets

Salty nuts, crisps, and olives are all great to snack on to keep your salt levels up. You can also make sure to season your food with salt before eating. 

Speak with your CF team about taking salt tablets, they will advise you of what you need. 

Symptoms of dehydration in adults:

• Tiredness or lack of energy
• thirst
• difficulty concentrating
• dark yellow or strong smelling pee
• peeing less often
• feeling lightheaded or dizzy
• a dry mouth, lips and tongue
• sunken eyes

Babies and children

Babies and children are even more likely to be affected by hot weather. Like adults, children with CF will sweat more and will be at risk of dehydration and salt loss. Keep them well hydrated by drinking lots of fluids. Keep up salt levels in older children with salty snacks and season food with salt. 

Symptoms of dehydration are different in babies and may include: 

• a sunken soft spot (fontanelle) on top of their head
• sunken eyes
• few or no tears when they cry
• not having many wet nappies
• being drowsy or irritable

The NHS website has more information about dehydration.

Some medicines, such as antibiotics, increase your skin’s sensitivity to sunlight. This means your skin is more prone to sunburn and at higher risk of skin cancer. To protect your skin, use a high factor (50+) sun cream and remember to re-apply every two hours and after swimming. Wear clothing that covers your skin and stay in the shade. 

Even waterproof sun cream does not last for long in water so if you are swimming, or are in and out of water, try wearing a rash vest or long-sleeved bathing suit with a sun protection rating to protect you from the sun.

Some of the antibiotics that cause skin sensitivity include: 

• ciprofloxacin
• doxycycline 
• voriconazole. 

Check with your CF team if any of the medications you are taking cause sun sensitivity.  If you are taking these medications, or you experience sun sensitivity, you should avoid exposure to sunlight or the use of sun beds.

Babies and children

You should take extra care to protect babies and children, as their skin is much more sensitive than adult skin. Babies less than 6 months of age should not be exposed to direct sunlight. Limit time in the sun for older children and always use a factor 50+ sun cream and clothing with a sun protection rating if they are outside for long periods, especially when playing in water.

Diabetes can be affected by hot weather. You may be more likely to experience both high and low blood sugar levels. Some of the symptoms of a hypo (hypoglycaemia or very low blood sugar) such as sweating or tiredness may be similar to how you feel in the heat. Be sure to check your blood sugar levels more regularly to avoid this. In hot weather, insulin may also be absorbed more rapidly, making hypos more likely. 

Insulin is heat sensitive so be sure to keep it out of the sun with your other medications. Meters and test strips are also sensitive to heat and cold, so keep them somewhere at room temperature and out of direct sunlight. 

Being dehydrated can have even more impact on you if you have diabetes; make sure to follow the advice about staying hydrated and avoid sugary drinks. 

You may use exercise to help manage your diabetes but be sure to follow our advice about exercising in hot weather below.

Check out Diabetes UK for more information about diabetes in the sun.

Hot weather can affect air quality. Higher temperatures can increase levels of pollutants in the air we breathe, such as Ozone (O3). This increase in pollution can irritate our airways and if you have asthma, increase exacerbations. 

Heat and increased air pollution can also increase the amount of pollen that plants produce, which can affect seasonal allergies if you have them. Thunderstorms, common in summer, break down the pollen, so it is inhaled more deeply into the lungs. 

Finally, hot weather also increases this risk of wildfires, even in the UK. In recent years we have seen lots more wildfires with longer periods of hotter, drier weather. This negatively affects air quality and can make symptoms worse. Be careful when you are out and about not to contribute to this by not leaving rubbish in the countryside, especially glass. Do not have barbeques or fires outside of designated areas and follow the Fire and Rescue Service advice for more information on fire safety. 

Make use of the Heat-health alert service. Developed by the met office and the UK Health Security Agency, the service alerts you to extreme weather and the impact that might have. 

Kaftrio can improve the balance of salt and water in your cells; however, this will vary between people. Speak to your CF team for individual advice.

Take extra care if you are exercising in hot weather. As you sweat more when exercising, salt levels can drop more quickly. Avoid exercising during very hot weather or in the hottest part of the day. Early mornings can be cooler or exercise indoors if there is air conditioning which may help.

A lot of medications, especially enzymes and insulin, are sensitive to heat. Most drugs will say on the packaging what their temperature range is. Make sure to keep them within this range. This may mean keeping them in a cool bag when you are out and about. Make sure you do not leave them in your car or in direct sunlight. 

• Keep out of the sun between the hours of 11am and 3pm. 
• Try to rest during the hottest time of the day. 
• Children and adults should wear a hat in the sun as well as high protection sun cream.

If you are travelling to a hot country, it is important to let your CF team know as soon as possible in case you need to take any supplements with you.

Hot air temperatures may make it feel harder to breathe. Using a fan can help with this by keeping the air moving and making it feel a bit cooler. Damp towels placed on your skin or using a foot bath with cool water can help to cool you down.