Why Did an Antihistamine Calm My First MS Attack?

I still vividly remember my first MS attack.

I developed severe optic neuritis and lost all vision in my left eye. My legs were weak and tingling, I had a terrible headache, I could barely sleep, and the fatigue was overwhelming. I could not care for my family, let alone myself. Thank goodness my mother stepped in to help us.

I was diagnosed with MS by a neurologist at a leading MS hospital clinic in Canada. He gave me no hope for a cure and stated that I would become completely disabled in time.

Shortly after my diagnosis, a friend introduced me to a neurologist in the Netherlands who recommended something I never expected: a sedating antihistamine.

Dr. Maas was using antihistamines and dietary changes to manage her MS patients nearly 40 years ago.

Upon this doctor’s recommendations I decided to try the antihistamine as it was safe and over the counter. It helped me a lot!

I was able to sleep. I felt calmer and more peaceful. The intense response inside my body seemed to settle, and I became more stable.

It did not cure the MS, but it helped me stabilize and became an important first step in my integrative recovery journey.

Antihistamines do more than treat allergies

At the time, I had no idea why the antihistamine helped me so much.

Today, research shows that histamine and its receptors are involved in inflammation, immune activity, the blood-brain barrier, myelin-producing cells, and other processes relevant to MS. The effects are complex and can vary depending on the histamine receptor involved.

One case-control study found that people who had used sedating antihistamines before the onset of MS had lower odds of developing the disease. The researchers described this as a possible beneficial effect, not proof that antihistamines prevent MS.

Another study has also investigated clemastine, a first-generation antihistamine, as a potential remyelinating drug. In a clinical trial, clemastine produced a small improvement in the speed of nerve signals through chronically damaged optic pathways.

That research gives us a much bigger picture. Certain antihistamines may impact inflammation that further influences neurological function in ways that extend beyond ordinary allergy relief.

Parasites can trigger strong histamine reactions

Parasites don’t sit quietly inside the body.

They can irritate tissues, interact with immune cells, and manipulate the immune response in ways that may help them survive. Histamine is one part of that relationship.

When histamine binds to H1 receptors, it can contribute to:

• Blood vessels becoming leaky
• Fluid leaking into tissues
• Itching, swelling, and sensory irritation
• Feeling hot, wired, or overstimulated
• Difficulty settling and sleeping

By blocking H1 receptors, sedating antihistamines can reduce some histamine-driven symptoms and promote sleep. This may help explain why the antihistamine helped calm my body during that first severe attack.

Antihistamines are not a full treatment for MS or parasitic infections. However, some practitioners use them as supportive tools when patients experience significant histamine reactions during infection treatment.

Certain antihistamines directly harm parasitic worms

This is where the research becomes especially surprising.

A 2024 study screened 21 H1 antihistamines against Angiostrongylus cantonensis, a parasitic worm that can infect the nervous system. Researchers identified several antihistamines that directly affected the parasite, including promethazine, cinnarizine, desloratadine, and rupatadine.

The active drugs changed larval movement and morphology. In other words, they did not merely calm the host’s symptoms. They acted directly against the worms in the laboratory.

This does not mean every antihistamine kills every parasite. It shows that specific drugs in this category can have direct anthelmintic activity against specific worms.

Blocking histamine can remove a worm’s survival advantage

Another study examined filarial worms, which which have been linked to MS.

Researchers found that blocking H1 receptors with fexofenadine reduced the number of adult worms and increased eosinophil activity at infection sites. Eosinophils are immune cells that help defend the body against parasites.

The findings suggested that histamine released during infection may help these worms survive by weakening eosinophil-mediated clearance. Blocking H1 receptors shifted the balance back toward the host’s immune defence.

This reveals two possible actions:

1. Some antihistamines can act directly against parasites.
2. H1 blockade may remove a histamine-based advantage that certain worms use to survive.

Antihistamines and Schistosoma blood flukes

Researchers have also tested H1 antihistamines against Schistosoma mansoni, a blood fluke that causes schistosomiasis.

In laboratory and animal research, certain H1 antihistamines:

• Reduced worm movement
• Damaged the worms’ outer surface
• Lowered worm burden
• Reduced egg production
• Reduced some effects of infection in animals

These findings provide another example of common antihistamine drugs showing activity against a major human parasite.

An allergy drug with antimalarial activity

Antihistamine research is not limited to worms.

A large drug screen identified astemizole, a second-generation H1 antihistamine, as a potent inhibitor of the malaria parasite Plasmodium falciparum. It acted against both drug-sensitive and multidrug-resistant strains and also reduced parasite levels in mouse models.

The drug accumulated inside the parasite and interfered with its ability to detoxify heme, creating a toxic environment for the organism.

Astemizole was removed from many markets because of serious heart-rhythm risks. It is not something to use as a do-it-yourself parasite treatment. Its importance here is as proof of concept: a drug developed for allergies can also possess strong antiparasitic activity.

What this means for MS

I believe MS is an infectious disease and that parasites can be part of its underlying cause. I have shared much research on this topic.

The antihistamine studies discussed here do not, by themselves, prove that parasites cause every case of MS. What they do establish is important:

• Histamine pathways are involved in processes relevant to MS.
• Certain antihistamines may influence neuroinflammation and myelin repair.
• Some H1 antihistamines directly damage specific parasitic worms.
• H1 blockade can improve immune clearance in a filarial worm model.
• Certain antihistamines have shown activity against blood flukes and malaria parasites.

That is a very different picture from the idea that antihistamines simply stop sneezing or itching.

Forty years ago, I only knew that an antihistamine helped calm my body. Today, the research gives us a much bigger clue about why it was so helpful.

Antihistamines are supportive, not a complete plan

This research should not be interpreted as a do-it-yourself antihistamine protocol.

Antihistamines differ in how they work, how sedating they are, and which additional receptors they affect. Their benefits and risks also depend on the person, the dose, other medications, and the type of disease involved.

Antihistamines may serve as short-term stabilizers and, in specific research settings, supportive tools against certain parasites. They are not a complete parasite treatment or a complete MS recovery plan.

Any decision about using antihistamines should be discussed with a qualified medical professional who understands your health history and current medications.

There are real solutions to recover from parasites today!

To restore health, we must focus on treating the cause of inflammation, which are parasites. First, identify the enemy (parasites), then support the body and treat the parasites while following a holistic approach. When parasitic infections are treated effectively, we can overcome inflammation or disease.

If you’re frustrated with the fact that our standard of care STILL doesn’t offer a real solution for treating MS and other diseases, then click on the link below to watch Pam Bartha’s free masterclass training and discover REAL solutions that have allowed Pam and many others to live free from MS and other diseases.

CLICK Here to watch Pam’s masterclass training

 

 

References:

Langer-Gould A, Albers KB, Van Den Eeden SK, Nelson LM.
Allergy, histamine 1 receptor blockers, and the risk of multiple sclerosis. Neurology. 2006;66(4):572‑575. doi:10.1212/01.wnl.0000198507.13597.45.

Key findings: Case–control study showing that prior use of sedating H1 antihistamines in the 3 years before onset was associated with a markedly lower odds of developing MS, while allergic conditions themselves were not clearly linked to MS risk.

Link: https://pubmed.ncbi.nlm.nih.gov/16505314/

 

Green AJ, Gelfand JM, Cree BAC, et al.
Clemastine fumarate as a remyelinating therapy for multiple sclerosis (ReBUILD): a randomised, controlled, double‑blind, crossover trial. Lancet. 2017;390(10111):2481‑2489. doi:10.1016/S0140-6736(17)32346-2.

Key findings: In chronic demyelinating optic neuropathy due to MS, clemastine, a first‑generation antihistamine, shortened visual evoked potential latency, consistent with improved conduction and remyelination.

Link: https://pubmed.ncbi.nlm.nih.gov/29029896/

 

Amadio S, Parisi C, Martorana A, et al.
Repurposing histaminergic drugs in multiple sclerosis. J Neuroinflammation. 2022;19(1):140. doi:10.1186/s12974-022-02451-1.

Key findings: Review plus in silico work showing that histamine receptors (H1–H4) are involved in MS pathogenesis (microglia, BBB, oligodendrocytes) and that several histamine‑related drugs (including antihistamines) emerge as potential MS therapeutics in network‑based analyses.

Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC9181091/

 

Roquini DB, Lemes BL, Kreutz ALB, et al.

Antihistamines H1 as potential anthelmintic agents against the zoonotic parasite Angiostrongylus cantonensis. ACS Omega. 2024;9(28):31159‑31165. doi:10.1021/acsomega.4c04773.

Key findings: Screened 21 clinically used H1 antihistamines against the neurotropic nematode Angiostrongylus cantonensis; identified promethazine, cinnarizine, desloratadine, and rupatadine as active, with promethazine most potent, causing significant changes in larval motility and morphology.

Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC11256074/

 

Xavier RP, Silva LM, Santos FLN, et al.
H1‑antihistamines as antischistosomal drugs: in vitro and in vivo studies. Parasites Vectors. 2020;13(1):245. doi:10.1186/s13071-020-04140-z.

Key findings: Demonstrated that several H1 antihistamines have antischistosomal activity against Schistosoma mansoni: they impaired worm motility, induced tegumental damage, and in mice reduced worm burden and egg output.

Link: https://link.springer.com/article/10.1186/s13071-020-04140-z

 

Sullivan DJ Jr, Gluzman IY, Goldberg DE, et al.
A clinical drug library screen identifies astemizole as an antimalarial agent. Nat Chem Biol. 2006;2(8):415‑423. doi:10.1038/nchembio806.

Key findings: Screening 2,687 approved drugs against Plasmodium falciparum identified astemizole, a second‑generation H1 antihistamine, as a potent inhibitor of both chloroquine‑sensitive and multidrug‑resistant parasites, with in vivo efficacy in mouse malaria models, acting via accumulation in the food vacuole and interference with heme detoxification.

Link: https://pubmed.ncbi.nlm.nih.gov/16816845/

 

Mastin A, Dávila AMR, Xavier RP, et al. (example from earlier worm work)
Histamine 1 receptor blockade enhances eosinophil‑mediated clearance of adult filarial worms. J Immunol. 2015;195(2):704‑713. doi:10.4049/jimmunol.1500571.

Key findings: In a Litomosoides sigmodontis filarial infection model, H1 blockade with fexofenadine decreased adult worm burden and increased eosinophil recruitment; data support that histamine normally promotes parasite survival, and blocking H1 tilts the balance toward worm clearance.

Link: https://pubmed.ncbi.nlm.nih.gov/26204515/