Can Antihistamines Calm Restless Legs? A Personal Story

When quitting a simple allergy pill turns everything upside down.

For the past few months, I’ve been experimenting with various supplements. Right now, I’m taking iron, magnesium, and folic acid. I recently completed an 8-week vitamin D course and got a B12 injection last week. In short: my vitamin levels are being fine-tuned quite a bit.

My Theory: Allergies Fuel My Restlessness

Because I strongly suspected that my allergies were behind my mental and physical restlessness, I started taking antihistamines late last year. First, I tried prescription meds like fexofenadine and desloratadine. But they made me feel incredibly sluggish, dizzy, and off-balance. I actually had to stop taking them after just a week or two because walking around became tricky—I just didn’t feel stable.

Then I remembered cetirizine. It’s an over-the-counter antihistamine I’d used years ago during a rough hay fever season. I gave it another shot—and to my surprise, it went okay. No intense side effects. Of course, I still noticed subtle changes (I’m very sensitive to medications), but it wasn’t disruptive. So I kept using it for a while.

The Nap Habit

A few weeks in, I started getting drowsy—mostly in the early afternoon. Not shocking for someone with chronic sleep issues. But something felt off: I was actually starting to sleep a bit better at night, so why was I still so sleepy during the day?

Eventually, I gave in to the feeling. I work from home, so I’d crash on the couch for 30 minutes with an alarm. These micro-naps actually helped—I felt refreshed enough to carry on with the day.

This nap routine lasted for a few weeks. It was manageable. But I couldn’t shake the question: Is this just residual fatigue—or something else? Around the same time, my bloodwork came back showing very low iron levels, even though I supplement daily.

Then I remembered: antihistamines can cause drowsiness too. So I decided to stop taking cetirizine for a few days and see what would happen.

Four Days Without Cetirizine: A Total Switch

The result was not what I expected.

Roughly 24 hours after stopping cetirizine, I had a very restless night. I felt wired, jittery, unable to sleep—like I was running on adrenaline or had a caffeine IV drip. It was a familiar sensation I hadn’t felt in weeks.

The second night was the same. Hyper-alert, buzzing energy. During the day, my brain was all over the place. I couldn’t focus, jumping from one thing to the next. I even caught myself talking out loud during a game of Call of Duty—much to the annoyance of my partner.

What was happening?

The Crash

Today, I worked on-site with colleagues and felt super hyper again—until early afternoon, when I suddenly crashed. My energy tanked. I packed up and went home to continue working there.

Once home, I tried to do my usual 30-minute nap. But no luck. Even though I was exhausted, I couldn’t fall asleep. My mind was buzzing again. And then—my legs started acting up.

Restless Legs Syndrome in full force. I couldn’t sit still. Twitching in my arms, shoulders, neck. The tears came. I felt overwhelmed by frustration, exhaustion, disappointment—and yes, anger.

Were Things Actually Getting Better?

Just a few weeks ago, I felt like something was shifting. The symptoms were still there, but they felt less intense. My legs had been calmer. My thoughts quieter at night. It felt like maybe I was making progress.

But today? That hope collapsed.

Could it be that cetirizine was actually calming my nervous or immune system somehow? I took a tablet again today, hoping I can return to the calmer version of myself I had briefly gotten to know.

Looking Ahead

In August 2025, I have a new appointment with an allergist—my second. The first one spent 10 minutes with me, barely listened, and sent me home with nothing. No testing. No discussion. No next steps.

I tried talking about histamine, mast cells, restless legs, and allergies—and it felt like I was speaking Chinese to a German. Nothing landed.

But this new allergist is at a different hospital. A fresh start. New hope.

Anyone Out There?

If you recognize yourself in any part of this story—or have insights, ideas, or your own theory—I’d love to hear from you. Sometimes, the smallest clue can bring the biggest relief.