Fast forward to one month later. It’s the first week in February and I’m off to Madrid to work at a conference for one of my regular clients. I’m out there from early Thursday morning until midnight on Saturday and it’s busy – very busy – seven hours sleep in three days and working the rest of the time. Not hard physical work, but tiring all the same. When I get back I’m pretty exhausted, but nothing you probably wouldn’t expect after such a long weekend.

I give myself Sunday and Monday off and write up a meeting report on Tuesday. New work from the same client arrives on Wednesday – I’m to write a formulary pack for a drug. I’ve worked on both the drug and other formulary packs before, so it shouldn’t be too challenging. Yet I sit at my desk, listlessly moving my mouse around and looking at the piles of resources and information that I’m supposed to be weaving into a justification of the benefits and costs of this product. Just two weeks ago, I would have whipped this background material into a coherent document without too much effort but now you might as well be asking me to run a marathon.

During the week, I have a few moments of utter exhaustion, almost falling asleep at my desk. Alarm bells are beginning to ring, but I tell myself it’s the last remnants of tiredness from the trip to Spain. By Friday, I’m mentally and physically exhausted. Hot spells, cold spells, nausea, joint pain and dizziness are haunting me. I crawl into my bed at 2pm Friday, realising that the chances of me writing anything worthwhile are zero – I tell myself I’ll work over the weekend. I’m still hoping that I’m just overtired from the trip to Madrid – although the logical side of my brain is telling me it is more than that.

I rallied around a little on Saturday, feeling well enough to drive into town to get a Valentine’s card for my husband and attend an optician’s appointment. In the evening we go to an old schoolfriend’s concert and the aftershow party, and I’m still feeling ok. By Sunday morning, though, I’m exhausted again. My joints are aching and swollen – hips, neck, knees, shoulders – and I keep having spells of lightheadedness and nausea. Despite the overwhelming tiredness, I struggle to sleep, unable to find a comfortable position in bed.

The only sensible conclusion now is that I’m having a flare up of my colitis, although my bowel itself is generally behaving itself. I’ve upped my dose to two tablets a day again, but it will no doubt be a couple of weeks before the full effects kick in, so I’m waiting on a call from my consultant for advice.

Today is my 39th birthday – but the way my body is feeling, it might as well be my 99th.

I was diagnosed with colitis eight years ago after nine months of being very unwell. Fortunately I was not ill enough to be hospitalised, but the symptoms left me feeling unbelievably dreadful and seriously disrupted my everyday life. I soldiered on for months – scared of what was wrong and somewhat embarrassed about talking to my doctor – until I hardly dare leave the house.

My GP sent me off to the hospital, where I underwent a variety of tests, which confirmed the diagnosis. After trying a few different bowel-targeted drugs and the devil’s own medicine – steroids – my gastroenterologist prescribed me a drug called azathioprine. It was originally used in patients who have transplants to stop the body’s immune system rejecting the graft but it also works well in some patients with autoimmune diseases.

Within weeks I had relief from my symptoms and started to feel like a human being again. Colitis is not curable medically (though surgery can cure it) but I seem to be in remission. It took a while, I’ve had a few hiccups along the way and I have to follow a low-fibre diet to control the symptoms of the colitis as well as my irritable bowel syndrome. On the whole though, my life is pretty much back to normal. I love my azathioprine and would fight anyone who tried to stop me taking it, but it’s not without its downsides.

Azathioprine reduces the production of white blood cells – the cells of the immune system that fight infection. Because of this, I have the seasonal flu jab every year and this year the swine flu jab too. Azathioprine can also cause liver damage. I have blood tests every three months to check my white blood cells aren’t dangerously depleted and that my liver is working properly. In the long term, azathioprine could increase my risk of some cancers – though colitis itself increases my risk of bowel cancer.

But it’s the effect on my immune system that provoked this post. Last night I developed early symptoms of my fourth cold this winter. I only stopped croaking from a throat infection a couple of days ago. I’d developed that after a night out in London in mid December. The week before, I had finally shaken off the symptoms of another throat infection that started in mid November – after a night out in London. And so the pattern will continue until spring…when my hayfever takes over.

Last night, bunged up, red nosed, frustrated and tired of almost constantly fighting coughs/colds/throat infections, I wondered whether it is really worth taking azathioprine. Then I thought back to the days *before* and I knew that when I see my gastroenterologist on Wednesday for my annual check up, I’ll ask him for another year with my wonderful drug.