I remember everything about that morning—or as I call it in my mind, in highly scientific terms, the Day That the Shit Totally Hit the Fan. I was getting ready to go to the gym. Usually this was a cause for dread, but that day it was an exciting opportunity to wear the new shorts that had just arrived in the mail. Nothing like shiny new workout gear to get you out and about. I put them on and was about to head out the door when I noticed an intense burning sensation on my thighs. They had become covered, seemingly in seconds, in large, angry hives. I pulled off the new clothes—clearly, something must have gotten on them!—and ran for the shower. Eventually the hives calmed down. Allergic reaction, I assumed, as I returned the shorts to the store in record time. And, I thought, that’s that.

My body, it turns out, thought differently. The next morning there they were again. The hives, not the shorts. Only this time they didn’t go away. They spread. Within a few days my body was reacting to anything that touched it with mounting anger. It was like some awful internal cascade had been set off, and now nothing could put it back to where it had been before.

This wasn’t my first bout with crazed skin reactions. When I was 22, I was diagnosed with mastocytosis. I’d suddenly developed an incredibly painful, oozing J-shaped rash around my left breast. My dermatologist, oddly enough, was overjoyed. Apparently it was rare for the condition (where the body makes too many immune system components called mast cells, which create inflammation) to manifest quite like that in an adult. Fewer than one in 30,000 adults have mastocytosis to begin with, and typically the skin rashes are associated with a childhood onset. After confirming my diagnosis with a painful biopsy, he had asked if he could take photographs for a journal article. I agreed: I was in too much pain to give it much thought, and he just seemed so …gleeful.

The condition has never gone away for long. When I’m too stressed or tired—or sometimes just hot—a painful raised rash appears. Sometimes it erupts in lesions. It stays for weeks. And then, just like that, it’s gone for a year or two or three. The ailment is not an autoimmune disease in itself, but it does mean that my body systematically churns out an abundance of mast cells. Could they be going out of control in my newly developed full-body hives?

It wasn’t mastocytosis, my doctor declared at an emergency appointment. My levels of tryptase, an enzyme released by mast cells, were normal. My thyroid, though, was out of whack. Did I have Graves’ disease—an autoimmune condition where the immune system attacks the thyroid gland? Or perhaps Hashimoto’s, where basically the same thing happens but with the opposite result, too little thyroid hormone to Graves’ too much? And if so, where were the hives coming from? Thyroid hormone abnormalities are not connected to hives in most patients.

The world of autoimmune disease is a murky one, often filled with vague guesses. Taken together, autoimmune conditions are common, but many individual illnesses are rare and difficult to diagnose. Oftentimes the diseases strike in infuriatingly hazy ways. Lethargy in the limbs, for instance, could be multiple sclerosis or lupus, devastating but different diseases with a lifetime of debilitating, progressing pain.

A slew of tests followed after my urgent medical visit. They showed my thyroid wasn’t to blame. But nothing else was, either. I was shuffled from internists to dermatologists to allergists and immunologists. My sister, a doctor, got me in to see one of the best allergy specialists in the Harvard Medical School system. The result: a host of acronyms I couldn’t quite understand, all serving to rule out condition after condition. One of them, the chronic urticaria index, declared that I have “basophil reactive factors in … serum which supports an autoimmune basis for disease.” I asked what that meant. I was told it meant that … I have hives.

In the absence of answers, the hives continued their colonization of my body. My neck. My face. My eyes, swollen shut. The oral steroid doses increased more and more, along with many antihistamines, which knocked me out to the point where I could barely keep my eyes open. The topical steroid creams got ever stronger. They had huge warnings down the side, urging you to not use them too liberally or for too long, lest your immune system fall apart entirely. I gained weight. I slept too much or not at all. I couldn’t think straight for any stretch of time. My immune system was suppressed beyond recognition. And still the cause of the hives remained a mystery. (The shorts, just a coincidence, every specialist assured me, despite my fervent belief in cause and effect.) Idiopathic, read my final diagnosis: origin unknown.

Eventually the hives did recede. Not with any new prescription or diagnosis but with time. The idiopathic hives became rarer hives which became, one glorious morning, a memory. But a memory with no known cause and no real cure. A memory that, to this day, might come back at any moment, with provocation or without. For if you never know what caused it, what’s to keep it from recurring?

Autoimmune: “of, relating to, or caused by autoantibodies or T cells that attack molecules, cells, or tissues of the organism producing them.” So says the Merriam-Webster dictionary, referring to certain immune system elements. In layperson’s terms: attacked by your own body. Instead of your cells uniting against a foreign invader, they turn against one another. Most of the time we don’t know what causes it. We don’t know how to cure it. When it comes to the autoimmune, the unknowns far outweigh the knowns.

Here’s what we know. There are about 80 kinds of autoimmune diseases. Nearly four of every five affected people are women. Why? We’re not quite sure. Because here’s the other thing we know: autoimmune research is perennially underfunded. Maybe it’s because women suffer the most—and women have, historically, been often ignored in medical research. Maybe it’s because many conditions are rare. Maybe it’s because when a cause is unknown, it is often assumed to be psychosomatic. You make yourself sick. You stress yourself out too much. Are you sure you aren’t just making it up?

My sister was thus accused. In her senior year of medical residency, she developed a strange tingling and numbness in her fingertips. For months she ignored it. But the tingling got worse, and the numbness intensified. She went to a neurologist because these could be symptoms of multiple sclerosis. Yet when an MRI test failed to show nerve abnormalities, a doctor said her numbness and pain weren’t real. It was all in her head. When she asked for pain medication for what by that point was neuromuscular agony, she was dismissed.

Remember my sister is a physician, with the professional vocabulary to precisely describe what to others would have been hard to capture. And this is what she was met with: disbelief, a medical response familiar to many patients with autoimmune conditions. She pushed back and eventually got a nerve-conduction test. The results were grossly abnormal. She hadn’t been lying or pretending. She had CIDP, chronic inflammatory demyelinating polyneuropathy, a rare neurological ailment with autoimmunity features. It causes pain, fatigue, and, in patients like my sister, permanent nerve damage. I can only imagine what would have happened to someone without her medical knowledge and wherewithal.

The world of autoimmune disease is a tough one. It’s not just the disbelief. Even with a diagnosis, relief can be elusive. A label is no guarantee of a cure. For CIDP, there is no disease-specific treatment. More than 10 years later my sister is still being treated with a medication developed for MS. Her condition remains understudied and underfunded.

She does have a label, though. I never got one. But here’s what I do know. No matter how visible or invisible any given condition, autoimmune disease is incredibly real, incredibly painful—and incredibly underappreciated by those who don’t suffer from it. Millions of people are casualties of that lack of awareness.

Here’s my wish: that one day I will no longer have to worry whether the next item of clothing I put on will knock me out for another year because someone, somewhere, will have studied what it is that makes me so sick. That one day my sister will be cured. That one day all the countless sufferers who have been told they’re imagining their symptoms are actually listened to—and that when they are, there are tools to help them. Our bodies attack themselves. Let’s finally listen. Let’s support the research needed to fight back.