This depends on how bad it is. If you have it mildly, you may feel perfectly well, and your rash may just be slightly uncomfortable.
If your erythema multiforme is more severe, you may have a fever and a headache, and feel unwell for a few days before the rash appears. Blisters on your skin may break down and leave painful raw areas. If your eyes are affected, you may become sensitive to light and notice blurring of your vision. Raw areas inside the mouth can make it hard to eat and drink, and genital soreness can interfere with passing water. Even when the rash has cleared up, a few people are left with scars on their skin, or with damaged eyes.
No one can guarantee that erythema multiforme will not come back, particularly if it follows recurrent cold sores. However, most patients with erythema multiforme recover completely.
In mild Erythema Multiforme
- The spots usually come up over the course of 3 or 4 days, starting on the hands and feet, and then spreading up the limbs to the trunk and face.
- At first the spots are small, round, slightly raised red areas, some of which turn into the ‘target lesions’ described above.
- These are 1-3 cm across, but may fuse together to produce larger areas. Small blisters form in the centre of some of the targets.
- The rash usually fades over 2 to 4 weeks, but recurrences are common.
In severe Erythema Multiforme
- You may feel ill and have a high temperature.
- The spots are usually larger, and run into each other more than those of mild erythema multiforme, but ‘target lesions’ can usually still be seen.
- Large blisters may form, and then burst to leave red oozing areas.
- Your lips may be covered with crusts, large raw areas may appear inside your mouth, and your eyes may swell up and turn red.
Diagnosing Erythema Multiforme
There are no specific blood tests for erythema multiforme. The diagnosis is usually based on the way the rash looks, the way it is distributed symmetrically over the skin, and exposure to one of the known triggers discussed above. Occasionally it is necessary to remove a small sample of skin under a local anesthetic to confirm the diagnosis under the microscope.