Taking theophylline for asthma

Find out when theophylline is used for asthma, how to use it safely, and the side effects to watch out for.

What is theophylline?

Theophylline is a type of medicine called a bronchodilator, which means it opens your airways. It can help some people to manage their asthma better.  

Theophylline is not a steroid medicine. You still need to take your usual corticosteroid preventer medicine and any other add on medicines prescribed for your asthma to help you avoid symptoms.

Your GP may prescribe theophylline if your asthma is not well controlled with your usual steroid preventer, plus other add on treatments.

You also need to use your reliever inhaler (usually blue) to deal with symptoms getting worse. Theophylline cannot help if symptoms get worse or you have an attack. Make sure you keep your reliever inhaler with you at all times, so you can use it if you have an asthma attack.

Can anyone with asthma take theophylline?

Although theophylline works well for some people, it’s not suitable for everyone.

For example, it may not suit you if:

  • you’re older because the medicine takes longer to clear from your blood so may not be at a safe level
  • you’re a child unless prescribed under specialist care
  • you have other health conditions including high blood pressure, heart problems, stomach ulcers, liver problems, or alcohol addiction
  • you take other medicines including antibiotics, betablockers, oral contraceptives, some vaccines, and anaesthetics. Even after you’ve started theophylline, remember to tell your GP, dentist, or pharmacist you’re taking it, because it could affect what they can prescribe.

Taking theophylline safely

Go for blood tests 

It is important to go for regular blood tests to make sure that the theophylline in your blood stays at a safe level. Depending on the results of the tests, your dose may need to be adjusted.

Theophylline can be toxic if levels build up in the blood

Your GP or asthma nurse should arrange for you to have a blood test five days after you first start taking theophylline and at least three days after any dose adjustment.

You’ll also need regular blood tests to check that you’re taking the correct dose.

Take theophylline regularly, exactly as prescribed 

Theophylline is usually taken every 12 hours. If you don’t take theophylline exactly as prescribed, it could put you at risk either by taking too little, or too much.

If you’re unsure, make an appointment to see your GP or asthma nurse as soon as possible so you can ask. You can also ask your pharmacist.

If you forget to take a dose, check the patient information leaflet that came with your medicine. Never take a double dose to make up for a dose you’ve missed. Theophylline can be toxic if taken at high levels.

Swallow tablets whole 

If you’re taking theophylline as tablets, always swallow them whole with a drink of water. Crushing or chewing them is dangerous because your body will absorb the medicine too quickly and could lead to an overdose.

If you’re not sure about the best way to take your medicines, always check the patient information leaflet, or ask your GP, asthma nurse, or pharmacist.

Don’t switch brands 

Make sure you get the same brand of theophylline each time you pick up a new prescription.

This is because the amount of theophylline absorbed by your body varies between brands.

If you start taking a different brand to the one you normally have, you may be getting too much or too little of the medicine you need.

For example, if you have changed from the discontinued drug Phyllocontin, to theophylline tablets (Uniphyllin Continus) you may also be told to take a different dose. Your GP should monitor drug levels in your blood to make sure the new drug is working well for you.

If your GP or asthma nurse thinks the risk of side effects outweighs the benefits you might get from theophylline, they will look at different treatments to help you manage symptoms.

Phyllocontin® (aminophylline) has been discontinued in the UK.

If you’ve been prescribed Phyllocontin® for your asthma, your GP or asthma nurse will contact you about your options, which may include switching to Uniphyllin Continus which are alternative theophylline tablets.

Review your asthma medicines regularly 

When you’re taking theophylline, it’s important to go for regular reviews to check the medicine is still working well for you, especially if you’re also taking other medicines.

If theophylline has had no effect after you’ve been taking it for six weeks, then it’s probably not the right medicine for you. You and your GP or asthma nurse will need to discuss other treatment options.

If it is not helping you, or it’s making you feel unwell, your GP will need to change your treatment plan.

If you’re pregnant, planning to get pregnant, or breast feeding speak to your specialist, GP, or asthma nurse, as theophylline may not be suitable for you.

Interactions and side effects

At the right dose theophylline suits most people, but it is known for having a higher risk of side effects and interactions if the dose isn’t right. That’s why it’s important to have blood tests to reduce the risk.


Theophylline can interact with things like caffeine, over-the-counter drugs, herbal remedies, and alcohol. This can affect how the drug works for you and whether it is still safe for you to take it.

Talk to your GP if you have any concerns, for example how much tea, coffee, and other caffeinated drinks you can have or if you need to avoid them altogether. You’ll also need to be open with your GP, or asthma nurse, about how much you smoke, drink alcohol or use recreational drugs.

Side effects 

Your GP may consider other treatments before theophylline because of the higher risk of side effects.

If they do prescribe theophylline, your GP will want to review your treatment plan regularly to make sure it is still a good option for you. You’ll also need regular blood tests to check that you’re taking the correct dose.

Ask your GP or asthma nurse to talk through possible side effects. These will also be listed in the patient information leaflet that comes with your medicine.

Side effects of theophylline can include:

  • headache,
  • nausea, stomach upset, or vomiting
  • not sleeping well
  • increased heart rate
  • skin rash
  • seizures.

See your GP or call 111 if you have any of these side effects. Your GP can monitor your blood, change the dose you’re taking, or consider other treatments that might suit you better.  


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