Any insight or advice into how long C... - Asthma UK communi...

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Any insight or advice into how long Clenil takes to work, and when to step up medication?

LRLR profile image

Hi all, I have had two different medical opinions and so just wondered if anyone could offer any insight before my review tomorrow.

I am new to asthma and have been put on Clenil 16 days ago. I was also given a 5 day course of prednisone steroid tablets at the same time. The Pred made me fully better for 3 days! But since then I have gone back to having mild to moderate asthma attacks every other day, fatigue, headache, dry caugh every day and unable to do high intensity exercise. SoB every morning and evening and relying on ventolin everyday.

One medical practitioner told me the clenil has not had time to kick in properly yet and I need to wait and manage this. However, My GP has said the clenil should be working by now and has said we can go to step 3 preventor-Fostair.

Does anyone know who is right with this? Or is it unknown and opinions?

If I do swap to fostiar does it mean my symptoms will be even worse while I wait for the fostair to work and withdraw from clenil? Or does fostair work straight away?

Also is fostair very strong and are their side effects?

Thanks so much!

12 Replies

My understanding is that it takes a month or two to see the full benefits of inhaled steroids (like clenil), though you do typically see some improvement after a few weeks. Having said that, some doctors do now go straight to low doses of combination inhalers (like fostair), as you see much more immediate effects with these. The other medication in Fostair (formoterol) kicks in much more quickly and has a different mechanism of action, so you're likely to see faster improvements.

And no! The steroid base (type of steroid) is the same in clenil and fostair, so changing to fostair won't 'undo' the effects of clenil so far. Fostair also has smaller particles and is stronger than clenil, so should hopefully have more of an effect for you.

Side effects are (from reading various people's experiences) slightly more common with fostair, though these tend to be mild and short-lived for most people. The only side effect I've personally had from fostair is a slight tremor for a couple of hours after taking it (similar to the tremor I get from ventolin). If you do a search on this website for fostair side effects you'll be able to see other people's experiences!

I would say it's up to you what you decide to do, as neither doctor is 'wrong' so to speak. If you're really struggling, it might be worth going straight to fostair now, but if you'd prefer to wait and see if clenil makes more of a difference in the next couple of weeks that's probably also ok.

Hi Xiave

Thanks so much for this that has really put my mind at rest. I am back at work Monday so trying to get sorted for then and was worried about getting back to square one.

So the fostair sounds good then in that it can have immediate effects. I am really struggling and worried about feeling like this and working so I think it will be a good option.

Thanks so much I can’t tell you what a relief it is to get some insight before my review.

Yes 8 weeks or so is common for fully embedding of any new inhaled steroids. It's common to need extra ventolin in that time (one would assume over time that vent need would lessen and clenil would feel more effective). Side effects also tend to lessen and indeed disappear over the embedding time.

A common error in trying new meds is not allowing the time for all these things to happen. Not necessarily patient error either (although some people do seem to think ooh I have symptoms after a week, it's terrible, when it's not really going to be doing much by then lol) - but often docs/nurses don't even allow the time. Ok things might need to be different if not right or sufficient, but testing things out appropriately is important. Honestly at 16 days I wouldn't expect it to be suddenly working and would give it more time. Maybe call Asthma UK and see what their advice is though?

EmmaF91 profile image
EmmaF91Community Ambassador


Sorry to hear you’re having a rough time atm. New inhalers can take up to 8-12 weeks to fully kick in but by 4 weeks you should be feeling the benefit. 16 days isn’t really enough time for it to kick in.

I’d also suggest giving AUK a call and talking to them about things. The nurses are great and can be reached on 0300 2225800 M-F 9-5. Alternatively their WhatsApp service is 07378 606728.

Also below are some links you may find helpful where the topics have been written about before.

For some general information about inhalers;

And for more about add ons;

Something for ‘new’ asthmatics;

And also something to help you work out when things should be done 😉;

Hope this helps

Sorry me again 😅

Just wanted to add that it's promising the pred helped - so the inhaled steroids in the clenil should help once they kick in! Fingers crossed anyway 😀

Hi all

Thanks so much for your response this is really helpful. I felt conflicted and so took your advice and called the asthma nurses- well I was blown away! Within minutes of talking to me she asked if i had a cold- to which I said no. She told me she can hear congestion in my voice and believes it is ‘rhinitis’ triggering my asthma coursed by allergies!! She has advised I ask for a nasal steroid spray ASAP along with daily antihistamine (I am doing already) and said that yes the Fostair would be a really good choice under these circumstances (rhinitis) and because I am using so much ventolin the Fostair would be longer acting and also mean I get off the high does of clenil I’m currently using.

I think she implied the clenil may not be working so well because I am not addressing the rhinitis.

I could not believe how amazing she was noticing this over the phone- I have been seen by lots of Gp’s and medical staff and no one noticed this congestion I have- not even myself as it comes and goes quickly.

I feel so lucky to have spoken with her and have some kind of diagnosis and a plan for treatment. Thanks so much everyone for your insight and reminding me to use the asthma nurses!! I am going to get reading the links you have sent now! Xx

Aww that’s great, fingers crossed you get somewhere! Let us know how you get on 😊

I’m afraid it’s trial and error . Everybody with Asthma appear to react differently to different inhalers . I swapped to fostair and it worked after about 5-10 days and I have now built up a good defence some find a different inhaler better . It’s just about what works for you and your symptoms. Work with your asthma nurse and test combinations out and if they don’t work go back and ask to try something else . Learn your triggers . For me it’s winter and damp . Sorry can’t advice further

ahfat41 profile image
ahfat41 in reply to Julesc12

I swapped to fostair nexthaler 100/6 one puff twice a day a year ago. It is seasonal winter asthma. With becotide and ventolin I used to take inhalers only in winter and stopped in spring. I have continued taking fostair all yr due to the pandemic. I am sure the asthma specialist told me I can take it on demand only in winter when I need it most. My mum told me it acts as a preventer and should be taken regular even with no symptoms. Pl how do you take yours? Thanks

twinkly29 profile image
twinkly29 in reply to ahfat41

All preventers should be taken regularly even when well - in most people. Those taking (on doctor's advice) seasonally need to make sure they've started it back up about 8 weeks before they would be symptomatic because it takes that time to kick in properly. It might be worth discussing with the Asthma UK nurses to see what they advise in your case? Literally taking it on demand in winter (with no time for build up beforehand) doesn't sound like it would be effective when you need it.

Thank you, that’s good to know about the fostair- wow it can work quickly then!

EmmaF91 profile image
EmmaF91Community Ambassador in reply to LRLR

Yup. The 8 weeks estimate is the steroid to kick in. But the LABA will start working almost straight away and should cut now the need for ventolin very quickly.

I’m really glad AUKwere so helpful for you too!

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