I was highly radioactive for a month after a thyroid treatment here's what it was like and all the rules I had to follow

I have Graves disease, which means my thyroid is overactive.

The thyroid controls metabolism — how quickly the body works. By spewing hormones into the body, thyroids affect how quickly body temperature, digestion, energy levels, how fast your heart pumps, and even how you think and feel.

When the thyroid makes too much of these hormones, the body goes into hyperdrive.

If not treated properly, Graves can lead to heart problems.

It's also really unpleasant. My heart would start racing unprompted, I would feel extremely hot in cold environments, my weight would drop or shoot up regardless of my diet, and it made me anxious and sad for no reason.

I also had to stop going to the gym and doing yoga for fear of putting too much strain on my heart.

There were strict rules to follow to avoid harming others:

• For three days: don't make food for other people, and increase personal hygiene.
• For 16 days: avoid staying within 6 feet of others for more than 30 minutes a day, sleep alone, and no kissing or sex.
• For 27 days: no close contact with pregnant people and children, no non-emergency medical and dental treatments, and no busy social situations.
• For six months: avoid getting pregnant.

Ahead of the treatment, I followed a low-iodine diet for two weeks to flush out iodine from my thyroid.

The thyroid sucks up iodine from around the body to make its hormones.

That's why radioactive iodine works so well to treat hyperthyroid: it rushes to the thyroid and has its effect there. The rest of the body gets relatively little radiation.

These are some iodine-rich foods I needed to avoid:

• Fish.
• Eggs.
• Processed meat.
• Sea salt.
• Milk and other dairy products.

By the end of the two weeks, I couldn't wait to eat a cheese sandwich.

I headed to the nuclear medicine department and was given the treatment in a fairly generic room.

It's carried around in a lead container to prevent others from being exposed. Staff wheeled it in on a cart.

The grabber has little claws at the bottom to grasp the pill in the container and is hollow so I could tip the pill back into my mouth without ever touching it.

As soon as I took the treatment, my Geiger counter started picking up radioactivity.

A technical disclaimer! To be completely accurate, Geiger counter readings need to be taken in a controlled environment after the machine was calibrated by a professional.

We didn't do this, so the data in this article is more of a ballpark than a precise measure.

All the same — moments after taking the pill, the radioactivity measure jumped to 1,300 times higher than the "background" level expected of an average person.

The doctor told me that the radioactivity then was mostly in my stomach and that as the pill was digested it would concentrate in my thyroid.

From this moment on, I had to avoid exposing others.

In some cases, hospitals decide to keep patients in special protected rooms for a few days.

But I live alone and could easily isolate, so my doctors let me go. I don't have a car, so I walked home on quiet streets.

I used the Geiger counter to measure radioactivity closest to the source: around the throat.

I found that radioactivity shot up at first, then dropped steadily over time, reaching normal-ish levels by the end of the treatment.

Radiation was strongest around my throat and decreased steadily as the detector was further away.

That means that those who were more than 6 ft away from me would get a lot less radiation than those who were very close to me.

During the first few days of the treatment, you're at your most radioactive.

The radioactive iodine that didn't bind to the thyroid is getting flushed out in body fluids.

This is mostly via peeing, but also through things like saliva, sweat, and poop.

During those first few days, you are asked to double flush the toilet. Any period pads or tampons should be double-bagged and thrown away immediately. You're also asked to use your own plates and not cook for anyone else.

Staying more than six feet from other people is trickier than I first imagined.

I don't have a car and was told to avoid public transport, so any outing from my apartment had to be within walking distance.

I could buy groceries so long as I moved around and left quickly, but had to avoid all non-essential contact.

I found the park was the only place I could spend a little time outside of my apartment while being far enough from others.

I even revived one of my pandemic hobbies: I re-upholstered an old chair and painted my kitchen walls.

During the first two weeks, my partner and I could only see each other for short periods of time, and while six feet apart.

It was harder than I thought to not have physical contact. We kept forgetting I was highly radioactive and going in for a hug before remembering we shouldn't.

Staying away from loved ones after a somewhat scary medical procedure was harder than I expected.

I'm French, and France's two-round presidential election was happening during the treatment period.

I realized there was no way I could safely stand in line to vote in the second part, a contest between Emmanuel Macron and Marine Le Pen.

I tried to vote remotely but found that still required visiting a voting center at a different time, which I couldn't do.

So I couldn't vote, which felt infuriating. (Macron won the election.)

A haircut takes more than 15 minutes. And when your hair grows fast like mine, going without means you end up looking pretty shaggy.

After two weeks of strict isolation, I was allowed to see adults but had to stay away from pregnant people and children.

That meant that any crowded places like pubs and cinemas were still out.

But I was desperate to get out of my apartment. I could go to places where it was OK to move around a lot. I found that my partner and I could go to some events together, as long as we knew they weren't going to be too busy.

At the end of my treatment, I went to a short gig where I knew people were going to be far away from me.

I explained the situation to my friends before they came, and they were OK with the small exposure. Measuring your radioactivity turns out to be a fun party trick.

After 27 days I was allowed to go back to life as normal. But I was still giving off a slightly higher level of radiation than normal.

I learned that airports have detectors to spot unnatural levels of radioactivity. So I was given a letter attesting that I was a little more radioactive than expected.

After a long flight from London, I set off gates at San Francisco International Airport that started beeping with bright lights. A border agent reviewed my documents and measured the radioactivity in my thyroid with a big Geiger counter.

Thankfully, he didn't think I was a safety risk and let me through.

After years of hyperthyroidism, my levels are down and almost back to normal!