"I told you," my best friend said, wearily. "It would only lead to trouble." No, she was not scolding me for a one-night stand or an impulsive phone call to an ex-boyfriend. She was referring to my having turned to the internet to self-diagnose.

When it comes to health concerns, going online for answers is the equivalent of having sex with someone on your first date. You know it's a bad idea, your friends tell you not to, but you can't help yourself, you do it anyway ... and you pay the price.

How did this happen? Before the internet existed, you didn't know what you were dying of until the doctor told you. Now you're online and having your medical questions answered as soon as the symptoms kick in, which ups the risk that you'll fear you're dying within seconds. And there's more room to speculate. You could have acid reflux or you could have lung cancer: the symptoms are the same.

For a while, I stayed away. I resisted looking things up because I knew where it would lead. What could I gain except panic, fear and friends who'd tell me I should have heeded their warning? But recently I had a setback. My dermatologist remarked that the "butterfly rash" on my face (a common sign of rosacea, which I've had for years) could be a symptom of lupus.

"I'm sure you're fine, but let's take blood to be sure," he said. And suddenly the rash on my face was the least of my worries. It was a Friday afternoon and the results wouldn't be through until Monday. This meant I'd have to live all weekend with the fact that I might have lupus. That's when my resolve broke down. Why suffer through a weekend of uncertainty when information was only a Google search away?

What a mistake. I typed in "symptoms of lupus" and there it was: number one, butterfly rash. I stayed calm. Maybe I didn't have any of the other symptoms. So I kept reading. Easy bruising, cold hands, headache. Yes, yes, yes. Bleeding gums, pain in back, shortness of breath. Yes, yes, yes.

Dry eyes, dry mouth ... the list was endless and I had everything on it. The only symptom I didn't have was joint pain. Just then, I got an ache in my elbow. I was a goner.

Here's why the internet is dangerous: 99% of people in the world have fatigue and headache, but when they appear online in a list of symptoms for an incurable illness, they seem infinitely more sinister. Moreover, one symptom invariably leads to a link for something else. For instance, dry eyes/dry mouth brought me to Sjogren's syndrome, a new syndrome I didn't even know I had.

Monday morning, my doctor calls. Good news, he says: you don't have lupus. "You didn't go online, did you?" I swore that I didn't. So now I'm lying to my doctor.

Fortunately, I'm not alone. There are millions of people out there freaked out from the internet and living in fear, just like me. Some of them are people I know; we've had similar experiences and discuss "going online" stories like war veterans reliving D-Day.

Recently Natalie, a woman I know, had a urinary tract infection and was prescribed the medicine Cipro by her gynaecologist. When, a few days later, it wasn't working, she sat down at her computer and looked up "burning urination". What appeared was an assortment of STDs. Syphilis, gonorrhea, chlamydia . . . where to begin. She promptly discovered that gonorrhea left untreated could lead to blindness. But "burning urine" also led her to a site for PID (pelvic inflammatory disease), which could make her infertile.

When she cancelled our plans, I had no idea it was because she was at home, crying, preparing to adapt to a life of darkness and shame. Convinced she was about to be blind and barren, she ran back to her doctor. Turns out that Cipro takes a few days to work and what she had was a urinary tract infection. Otherwise known as the original diagnosis.

Then there was Debra, who thought she had herpes. She left the following message on my voicemail: "I'm online and I have herpes, I know I do." Given that I, too, once thought I had herpes (checking online for herpes is a rite of passage for most women), I was set to reassure her. To begin with, avoid the testimonials. You're vulnerable as it is; do you really need to read about the virgin who claims she got herpes from a dirty towel?

I called her back right away. "Never mind," she said. "It's PMS." Both produce a tugging in the ovary; but only one leads to a lifetime of embarrassment, whereas the other leads to three days of cramps.

From now on, when I have the urge to look up a symptom online, I've decided to suffer the old-fashioned way: I'll look up an ex-boyfriend instead.