Antihistamine withdrawal symptoms typically last anywhere from a few days to 6 to 8 weeks, depending on which antihistamine you were taking, how long you used it, and whether you stopped abruptly or tapered off. The most common and well-documented withdrawal effect is intense itching after stopping cetirizine (Zyrtec) or levocetirizine (Xyzal), which the FDA now requires a label warning about. Other antihistamines, particularly older sedating types like diphenhydramine (Benadryl), can cause a different set of withdrawal symptoms including nausea, anxiety, and dizziness.
What Withdrawal Feels Like
The specific symptoms depend on which type of antihistamine you were taking. For newer, non-sedating antihistamines like cetirizine and levocetirizine, the hallmark withdrawal symptom is severe, widespread itching that has no visible rash or obvious cause. This itching can be intense enough to disrupt sleep and daily life, and it often feels worse than whatever allergy symptoms prompted the medication in the first place. The FDA identified 209 reported cases of this reaction between 2017 and 2023, and in nearly every case where people tried stopping the medication again, the itching came back.
For older, sedating antihistamines like diphenhydramine and hydroxyzine, withdrawal looks different. These medications have stronger effects on the brain and nervous system, so stopping them can produce nausea, vomiting, headache, sweating, anxiety, and dizziness. Symptoms from these sedating antihistamines can start within one to three days of reducing your dose.
How Long Each Phase Lasts
The timeline breaks down roughly into two phases. The first is the acute withdrawal period, when your body is actively adjusting to the absence of the drug. For sedating antihistamines, this begins within one to three days and typically peaks within the first week. For cetirizine and levocetirizine, itching often starts within days of the last dose.
The second phase is a longer tail of lingering symptoms. According to clinical deprescribing guidelines from the NSW Therapeutic Advisory Group, withdrawal symptoms from sedating antihistamines are “usually mild, highly variable, and can last up to 6 to 8 weeks.” Recurrence of allergy-like symptoms, such as itching, sneezing, and watery eyes, may appear within one to two weeks of dose reduction and can persist for several weeks as your body recalibrates.
For cetirizine-related itching specifically, the timeline is less predictable. Some people report resolution within a few weeks, while others describe symptoms lasting months. The FDA’s review did not establish a firm endpoint, and the underlying mechanism remains unknown.
Why Your Body Reacts This Way
When you take an antihistamine daily for weeks or months, your body adjusts to the constant suppression of histamine signaling. One likely explanation is that your histamine receptors become more numerous or more sensitive to compensate for the drug blocking them. When you suddenly remove that blockade, histamine floods receptors that are now primed to overreact, producing symptoms that are more intense than what you experienced before starting the medication.
For sedating antihistamines, the picture is even more complex. These drugs affect brain chemistry beyond just histamine. Animal research has shown that chronic use of diphenhydramine reduces levels of GABA, a calming brain chemical, in key brain regions. This reduction persists even after the drug is stopped, which helps explain the anxiety, restlessness, and neurological sensitivity that can follow withdrawal. The effect appears to last at least 10 days after cessation in animal models, and in humans, the full normalization period likely takes longer.
Cetirizine and Levocetirizine Are Special Cases
The FDA singled out cetirizine and levocetirizine for a reason. While withdrawal effects from other antihistamines are generally mild and self-limiting, the itching that follows cetirizine or levocetirizine discontinuation can be severe and remarkably persistent. Of the people in the FDA’s review who restarted the medication, 90 percent found that it resolved their itching, confirming the symptoms were caused by stopping the drug rather than by an underlying condition.
What makes this particularly frustrating is the cycle it creates. You stop the medication, develop unbearable itching, restart it to get relief, and then face the same problem when you try to stop again. In 92 out of 93 cases where people attempted to stop a second time, the itching returned. Tapering off after restarting only resolved symptoms in about 38 percent of people who tried that approach, which is better than quitting cold turkey but far from a guarantee.
How to Minimize Withdrawal Symptoms
The single most effective strategy is tapering rather than stopping abruptly. For sedating antihistamines, a gradual dose reduction over several weeks gives your brain and body time to adjust. Many clinicians recommend cutting your dose by 25 to 50 percent every one to two weeks, though the ideal pace varies from person to person.
For cetirizine and levocetirizine, tapering is trickier because the tablets aren’t always easy to split into smaller doses, and the evidence for tapering success is modest. Still, it’s worth trying. You can reduce from a full daily dose to half a dose (using a pill cutter or liquid formulations), then to every other day, before stopping entirely. If itching flares during a step down, hold at that dose for a few extra days before reducing further.
During the withdrawal period itself, cool compresses, fragrance-free moisturizers, and cool showers can take the edge off itching. Keeping your skin hydrated reduces the intensity of itch signals. Loose, breathable clothing helps, since heat and friction make itching worse. If you were taking an antihistamine for allergies, switching to a different class of antihistamine (like fexofenadine, which has not been flagged for the same withdrawal itching) before tapering off may help bridge the gap.
What to Expect Week by Week
In the first three days, withdrawal symptoms typically emerge. For sedating antihistamines, this means headache, mild nausea, and trouble sleeping. For cetirizine or levocetirizine, itching may start and escalate quickly.
During weeks one and two, symptoms usually peak. Itching is often at its worst, and you may also notice the return of allergy symptoms like sneezing and congestion, which can be hard to distinguish from true withdrawal. This is the period where the temptation to restart the medication is strongest.
By weeks three and four, most people using sedating antihistamines notice a significant improvement. The body’s histamine system is beginning to stabilize. For cetirizine-related itching, some people see improvement in this window, though others do not.
Between weeks four and eight, lingering symptoms from sedating antihistamines typically resolve completely. Cetirizine withdrawal itching is more variable. If your symptoms haven’t improved meaningfully by six to eight weeks, that’s a reasonable point to reassess your approach with a healthcare provider, since it may be worth trying a structured taper or switching medications before attempting discontinuation again.