Today we will be discussing the important topic of pharmacovigilance in general and specifically in relation to MS therapies. Multiple sclerosis is one of the neurological diseases that has undergone a transformation over the last 30 years from being untreatable to having a wide range of treatment options, especially in the relapsing-remitting form. Depending on the activity of the disease, disease-modifying drugs with low to high levels of efficacy are available.
Of course, it is important to be aware not only of the effects but also of the possible side effects, and to find the most suitable therapy for each patient. In this interview, Dr. Nora Möhn explains all stages of monitoring and safety from the development to the approval of a drug and how versatile pharmacovigilance is. This ensures that every person affected by MS has a clear understanding of how safety in MS therapies is guaranteed, monitored, and continuously improved. After all, a well-monitored, effective therapy that slows down MS contributes above all to a self-determined and fulfilling life in the long term.
The interview was published in September 2023 on the German MS-Perspektive podcast.
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Introduction of Nora Möhn
Dr. Nora Möhn: My name is Nora Möhn, I am 32 years old and have been working at the MHH in Hanover in the Department of Neurology (now Bonn University Hospital) since 2016. My clinical and scientific focus is on neuroimmunology and neuro-oncology. Among other things, I supervise the MS consultation hours and work in the MHH’s cerebrospinal fluid laboratory. I have been living in Hannover since my studies and feel very much at home here. In my free time, I enjoy meeting up with friends for a glass of wine or going to concerts. However, as I am in a long-distance relationship with someone in Halle (an der Saale), I spend a lot of time traveling on Deutsche Bahn trains, which doesn’t leave me much time for other hobbies.
Why did you choose this profession?
Nora Möhn: I had wanted to study medicine since 7th grade, when I was completely fascinated by the processes in the human body in biology class. At university and during my nursing internship, I quickly realized that becoming a doctor was indeed what I wanted to do later in life. I have been enthusiastic about neurology since my nursing internship, where I had a lot of contact with patients with neurological disorders. I find the subject incredibly diverse and exciting. The fact that you can find out a lot about the cause or origin of symptoms just by doing a physical examination makes neurology particularly appealing to me. And contrary to popular belief, many diseases can now be treated very well in neurology, sometimes with the most innovative therapeutic approaches—including MS, among others.
Introduction to pharmacovigilance
What does pharmacovigilance mean and why is it so important?
Nora Möhn: Pharmacovigilance basically refers to all activities and measures aimed at detecting, assessing, understanding, and preventing adverse drug reactions. Every drug has the potential to cause undesirable effects. It is extremely important to be as familiar with and able to assess these as accurately as possible in order to treat each patient effectively. As a rule, not all possible side effects are known when a drug is approved. It is therefore necessary to continuously and systematically record side effects even after market approval. The information obtained can be used to increase the safety of the drug in question.
How is safety data collected, and what precautions are taken early on in the drug development process to ensure drug safety?
Nora Möhn: Medicines are subject to strict regulations. Even before a medicine is approved, extensive safety data is collected. First, an active ingredient is tested in laboratory experiments and animal experiments requiring approval before it is administered to a small number of people for the first time in Phase I clinical trials. The subjects in Phase I trials are usually healthy individuals. The Phase I trial primarily tests the tolerability of the drug, i.e., whether it is generally suitable for use in humans. If there are any undesirable effects that are not tolerable, the clinical trial is stopped at this point.
If no such undesirable effects occur, Phase II trials follow, often involving approximately 100 to 300 people, in order to collect and evaluate initial data on the efficacy of a drug for the disease for which it is intended. Phase III trials are then usually conducted with a large number of participants in order to gather information about the efficacy and, in particular, the safety, i.e., frequent, occasional, or even rare (1:1,000) side effects of a drug. These controlled randomized clinical trials, in which the subjects in the control group are generally treated with either the standard therapy or a placebo, provide reliable results and form the basis for the initial benefit-risk assessment by the drug regulatory authorities during the approval process. As already mentioned, the collection of safety data does not end with market approval. Rare or very rare side effects can usually only be recorded once many patients have been treated. For this purpose, Phase IV studies are conducted and spontaneous reporting systems are used, among other things.
How and where can patients report adverse drug reactions?
Editorial note (Nele):
The original interview refers specifically to the German pharmacovigilance system (BfArM/PEI and the national reporting portal). For this international edition, the section has been adapted to reflect reporting systems in other countries. While the structure and terminology may differ, most countries have comparable national systems that allow patients and healthcare professionals to report suspected adverse drug reactions directly to their medicines regulatory authority.
Nora Möhn: In most countries, patients can report suspected adverse drug reactions directly to their national medicines regulatory authority through a spontaneous reporting system. Reports can usually be submitted online. Alternatively, patients may inform their treating physician and ask them to submit a report.
In the European Union, reports are collected nationally and contribute to the EMA’s EudraVigilance database. In the United States, reports can be submitted via the FDA’s MedWatch system.
🇪🇺 European Union
European Medicines Agency (EMA) – EudraVigilance
(central EU database collecting national reports)
Patients should report suspected side effects to their national medicines authority in their country. These reports are then transmitted to EudraVigilance.
EMA main website:
🔗 https://www.ema.europa.eu
🇺🇸 United States
Food and Drug Administration (FDA) – MedWatch Program
🔗 https://www.fda.gov/medwatch
Direct reporting page:
🔗 https://www.fda.gov/safety/medwatch-fda-safety-information-and-adverse-event-reporting-program
Patients and healthcare professionals can submit reports online.
🇬🇧 United Kingdom
Medicines and Healthcare products Regulatory Agency (MHRA) – Yellow Card Scheme
🔗 https://yellowcard.mhra.gov.uk
Patients and healthcare professionals can report online or via the Yellow Card app.
🇨🇦 Canada
Health Canada – Canada Vigilance Program
Online reporting is available for patients and healthcare professionals.
Monitoring and measures to improve safety in MS therapies
What measures are being taken to monitor, record, evaluate, and improve the safety and adverse effects of MS therapies?
Nora Möhn: All pharmacovigilance measures described above also apply to medicines used to treat multiple sclerosis (MS).
For MS therapies that have been on the market for many years, there is extensive clinical experience and broad knowledge about their potential side effects. Newer treatments have likewise undergone thorough preclinical testing and large clinical trials (Phase I, II and III) before approval.
Even after a medicine has been authorised, safety monitoring continues. Post-marketing (Phase IV) and other non-interventional studies are often conducted to detect rare side effects that may only become apparent when a larger number of people are treated in real-world settings.
If a side effect is suspected, healthcare professionals — and in many countries patients themselves — can report it through national online reporting systems (for example, in Germany via nebenwirkungen.bund.de/).
For certain MS therapies, additional safety monitoring programmes are in place. For example, with natalizumab, specific measures are implemented to monitor and reduce the risk of progressive multifocal leukoencephalopathy (PML), a rare but serious brain infection. These programmes include regular safety assessments and risk-minimisation strategies.
How do you weigh up the risk-benefit profile of disease-modifying therapies for MS, and how does this influence doctors' decisions when selecting and recommending treatments?
Nora Möhn: Before starting disease-modifying therapy, we first assess how active the MS is. The more active the disease (indicated by a high frequency of relapses, numerous lesions on MRI scans, spinal lesions, etc.), the more likely it is that highly effective therapies will be recommended, which may also have potentially more serious side effects. For us as practitioners, the risk of the patient becoming disabled as a result of MS usually outweighs the potential undesirable effects of the therapy. Of course, the individual factors of each patient (e.g., pre-existing conditions) and possible fears and concerns must always be taken into account. The decision to undergo disease-modifying therapy is always a joint decision that requires sufficient consultation and time for consideration.
Are there specific guidelines for physicians regarding the regular examinations required for a particular MS medication in order to prevent serious side effects?
Editorial note (Nele):
The following section has been slightly adapted for an international readership. The original interview refers to German regulatory structures (such as KKNMS and “Red Hand Letters”). To make the information applicable to readers outside Germany, the regulatory context has been explained and supplemented accordingly.
Dr. Nora Möhn: Yes, such guidelines do exist.
When a medicine is approved, the regulatory authority — in Europe, this is the European Medicines Agency (EMA) — defines which monitoring examinations are required and whether there are any restrictions on its use. Treating neurologists are expected to be familiar with these requirements and to discuss them with their patients.
In Germany, these monitoring recommendations are summarised by the MS competence network (KKNMS) in its “MS Quality Handbook” under the section “Monitoring & Measures.” For international readers: comparable guidance is provided in many countries by national neurological societies, MS organisations, or professional bodies, such as the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS) in Europe or the American Academy of Neurology (AAN) in the United States.
Pharmacovigilance remains crucial even after a medicine has been approved. If new information emerges from long-term observation or real-world data, a medicine may be reviewed by the Pharmacovigilance Risk Assessment Committee (PRAC) of the EMA. Monitoring recommendations — and in some cases even the approved indication — may then be updated.
In Germany, physicians are rapidly informed about new safety findings through official safety letters known as “Red Hand Letters.” Internationally, similar communications exist under different names, such as Direct Healthcare Professional Communications (DHPCs) within the European Union, FDA Safety Communications in the United States, or Drug Safety Updates in the United Kingdom.
What role do clinical trials and long-term observations play in the pharmacovigilance of MS therapies?
Dr. Nora Möhn: Clinical trials and long-term observations play a crucial role in this context. Before an MS therapeutic agent can be launched on the market and used by many, many patients, it must undergo various stages of clinical testing (preclinical (animal) trials and clinical trials in phases I-III). The drug is only approved if no serious side effects occur in these clinical trials. After market approval, so-called Phase IV trials or long-term observations are of great importance. Some rare side effects or interactions can only be detected when the drug is used widely, i.e., in many MS patients worldwide. This was the case, for example, with alemtuzumab (Lemtrada®) and, even more dramatically, with daclizumab (Zinbryta®). Based on the experience gained from long-term observations, the recommendations for the specific MS drug can and must then be adjusted. If the side effects are too severe, the drug may also be withdrawn from the market.
What additional precautions apply when using MS medications during pregnancy, in children and adolescents, and in elderly patients?
Dr. Nora Möhn: Pregnant patients, children/adolescents, and elderly patients are special patient groups. Since they are usually excluded from clinical trials, there is often no safety data on the use of the relevant drugs in these groups prior to market approval. Certain MS drugs are known to have a harmful effect on the fetus. These must not be used during pregnancy under any circumstances, and we must provide information about safe contraception during therapy. With other drugs, pregnancy may be possible, e.g., during a therapy-free interval, and must then be well planned.
In older patients, we must consider potential interactions with other medications and pay attention to things such as impaired liver or kidney function. Sometimes, in our opinion, the prescribed check-ups are not sufficient and we recommend more frequent laboratory tests.
Not all MS medications are actually approved for children/adolescents, as most MS therapies approved for adults have not been tested in randomized, controlled studies in children. Currently, interferons and glatiramer acetate are approved for adolescents aged 12 and older (Betaferon®, Avonex®, Copaxone®) and children aged 2 and older (Rebif®), as well as fingolimod (approved for the treatment of (highly) active relapsing MS in children and adolescents aged 10-18). In situations where these drugs are not an option, a decision must be made on a case-by-case basis, possibly including the use of an unapproved drug and, if so, particularly close monitoring.
Update (as of February 2026): In the European Union, teriflunomide (Aubagio®) is approved for children aged 10 years and older, and dimethyl fumarate (Tecfidera®) for adolescents aged 13 years and older with relapsing-remitting MS.
How can interactions between different medications be taken into account and monitored in MS patients?
Dr. Nora Möhn: For patients with other diseases in addition to MS, a detailed medication history must be taken before starting therapy with an MS drug. This helps to minimize potential interactions in advance. Patients should also inform their neurologist at an early stage if they need to take a new medication for another disease. There are specific programs into which the respective medications can be entered and then checked for interactions (at MHH, for example, “AiDKlinik”). Patients taking a variety of different medications may need to be monitored clinically and through laboratory tests even more closely than specified in the recommendations.
Information and resources on pharmacovigilance in MS therapies
What sources of information are available to doctors and patients for obtaining up-to-date information on pharmacovigilance in MS therapies? And what role do red-hand letters play?
Editorial note (Nele):
The original interview refers to German institutions such as KKNMS and the “Red Hand Letters.” For this international edition, the regulatory framework has been adapted to reflect comparable international pharmacovigilance structures and communication systems used in other countries.
Dr. Nora Möhn:
During clinical trials, investigators are informed directly by the study sponsor (usually the manufacturer of the medicine) about any relevant pharmacovigilance developments. In clinical research, all suspected adverse events must be reported promptly, and safety information is continuously shared between sponsors, investigators and regulatory authorities.
After a medicine has been approved and is available on the market, I personally rely on regularly updated guidance from professional MS and neurology organisations, as well as official communications from regulatory authorities, to stay informed about the latest monitoring recommendations. I also encourage my patients to consult reliable sources provided by recognised MS organisations and regulatory bodies.
Safety communications remain extremely important. At the time of approval, certain safety information — such as rare side effects, drug interactions, contraindications or specific risks in vulnerable patient groups — may not yet be fully known. Some risks only become apparent once a medicine is used more widely in real-world settings.
If new findings require immediate action by healthcare professionals, regulatory authorities issue urgent safety communications. Depending on the country, these may be called Direct Healthcare Professional Communications (DHPCs), Safety Alerts, Drug Safety Updates or Safety Communications. These letters are typically issued by the manufacturer in coordination with the relevant national regulatory authority and are distributed directly to healthcare professionals. In many countries, these communications are also published on the websites of the respective medicines agencies.
How can patients discuss concerns or uncertainties about the safety of their MS treatment with their doctor?
Dr. Nora Möhn: Those affected should be able to address such concerns and uncertainties in a low-threshold manner. Our goal as neurologists is to find the best possible and most suitable therapy for each individual. This can only be achieved if we provide comprehensive information and, at the same time, our patients openly express their concerns, e.g., during outpatient consultations. Sometimes it helps to make notes on the topics you want to discuss in preparation for your doctor’s appointment. I can only recommend addressing concerns early on and in an accessible manner! In retrospect, this certainly increases treatment adherence and is much better for both patients and us as neurologists than if there is no open communication.
Role of neurologists in pharmacovigilance
What progress has been made in pharmacovigilance to improve the safety and efficacy of MS drugs?
Editorial note (Nele):
The original interview refers to German MS research networks and registries. For this international edition, references to country-specific structures have been adapted to reflect broader international developments in MS research, pharmacovigilance, and safety monitoring.
Dr. Nora Möhn: The therapeutic landscape of multiple sclerosis (MS) has changed dramatically over the past years. An increasing number of effective therapies have been approved, offering neurologists and people living with MS a broad spectrum of treatment options.
On the one hand, this is a very positive development. It allows for more individualised treatment decisions, and today there is generally a suitable therapy option for most patients. On the other hand, the growing number of treatments can make the field increasingly complex. For neurologists, it is essential to stay continuously informed about new data, evolving safety recommendations, and updated monitoring requirements.
International MS research networks, academic collaborations, and real-world data registries contribute significantly to improving patient care and medication safety. Large observational studies and clinical registries help to better understand the frequency, characteristics, and long-term impact of side effects of both established and newer immunotherapies in routine clinical practice. Importantly, many of these initiatives involve not only physicians and researchers but also patients themselves.
In addition to academic efforts, pharmaceutical companies are also required to maintain comprehensive pharmacovigilance programmes. A well-known example is the safety monitoring programme for natalizumab. As many readers may know, natalizumab is associated with the rare but serious risk of progressive multifocal leukoencephalopathy (PML). Over time, specific risk factors for developing PML under natalizumab treatment have been identified.
Based on these findings, risk minimisation strategies were introduced, including enhanced monitoring recommendations and formal safety communications issued in coordination with regulatory authorities. Cases of PML occurring under natalizumab treatment are carefully documented and monitored internationally. From a pharmacovigilance perspective, natalizumab is often cited as an example of how structured, ongoing safety monitoring can improve risk awareness and patient management over time.
What is the significance of pharmacovigilance for patient safety and confidence in MS treatment?
Dr. Nora Möhn: Pharmacovigilance is crucial for patient safety. Only through the continuous recording and investigation of side effects and interactions can knowledge about the various therapeutic agents grow. Practitioners can then rely on this data together with patients when selecting a therapy. Without pharmacovigilance, it is not possible to make informed therapy decisions, and potential side effects during treatment could be much more difficult to classify. Pharmacovigilance is therefore essential for confidence in MS treatment.
How important are neurologists for pharmacovigilance and monitoring MS therapies?
Editorial note (Nele):
The original interview refers to German regulatory authorities and specific safety communication formats. For this international edition, country-specific structures have been adapted to reflect internationally comparable regulatory and safety communication systems.
Dr. Nora Möhn:
Neurologists play a crucial role in the treatment of multiple sclerosis. They determine the indication for therapy, counsel patients about the available MS treatments, and conduct regular follow-up examinations.
As specialists, neurologists are expected to be thoroughly familiar with the medicines they prescribe — including their potential side effects, drug interactions, contraindications, and specific monitoring requirements. This knowledge is essential to provide comprehensive patient education and to detect possible adverse effects early through appropriate clinical and laboratory monitoring.
In addition, neurologists receive official safety communications from regulatory authorities regarding newly identified risks or updated safety recommendations. These communications — depending on the country — may be issued as Direct Healthcare Professional Communications (DHPCs), Safety Alerts, or similar regulatory notices. Physicians must be able to interpret this information appropriately and inform affected patients without delay if changes in monitoring, risk assessment, or treatment strategy are required.
Quickfire round
Complete the sentence: "For me, multiple sclerosis is...
An incredibly interesting and challenging neuroimmunological disease, the treatment of which has seen tremendous progress over the last 10-15 years and which fascinates me every day anew.
What breakthrough in MS research and treatment would you like to see in the next 5 years?
I hope that, similar to the remarkable developments in the field of relapsing-remitting MS in recent years, a breakthrough will be achieved in the treatment of primary and secondary progressive MS.
Farewell
Is there anything else you would like to say to our listeners?
I would like to express my sincere thanks for listening and for your interest in this exciting topic. I would also like to encourage all those affected to openly express any concerns or worries they may have regarding drug safety/potential side effects to their healthcare providers so that an informed treatment decision can be made in consultation with them. The field of MS therapeutics can sometimes be very confusing and overwhelming, so it is essential to address any uncertainties and fears.
Where can you find her and her scientific work on the Internet?
My scientific publications can be found via PubMed by searching for “Nora Möhn” on the website of the U.S. National Library of Medicine (NIH):
https://pubmed.ncbi.nlm.nih.gov
Further professional information and updates can be found on my LinkedIn profile.
I hope you now know more about pharmacovigilance and feel confident enough to discuss any concerns or fears you may have about the treatments suggested to you with your doctor.
And remember, even though MS has become much less frightening, it is still a serious disease that should be slowed down as much as possible with medication and a healthy lifestyle. This will ensure that you can still lead a fulfilling life in several decades‘ time and won’t have to regret missed opportunities.
See you soon and try to make the best out of your life,
Nele
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