Biologics for psoriasis have a strong overall safety profile, and for most people the benefits significantly outweigh the risks. The most commonly reported side effects in clinical trials are infections, cold-like symptoms (nasopharyngitis), and headache. Serious adverse events do occur but are uncommon, and newer biologic classes appear to carry lower risks than older ones in several key areas.
How Biologics Work and Why That Matters for Safety
Biologics treat psoriasis by targeting specific proteins in your immune system that drive inflammation. Unlike older systemic drugs that broadly suppress immune function, biologics zero in on narrow targets. This precision is what makes them effective and, generally, safer than older options. But because the proteins they block also play roles in fighting infections and regulating other immune processes, there are trade-offs.
There are four main classes of biologics used for psoriasis, grouped by what they target:
- TNF inhibitors block a protein called TNF-alpha, one of the immune system’s primary alarm signals. Shutting it down reduces inflammation but also dials back defenses against certain infections, particularly tuberculosis.
- IL-17 inhibitors block interleukin-17, a protein heavily involved in psoriasis-specific inflammation. IL-17 also helps defend against fungal infections, so yeast infections (like oral thrush) are a known side effect.
- IL-23 inhibitors target interleukin-23, which sits upstream in the inflammatory cascade. Because they act on a narrower part of the immune system, they tend to have fewer off-target effects.
- IL-12/23 inhibitors block both interleukin-12 and interleukin-23, casting a slightly wider net than pure IL-23 inhibitors.
Infection Risk by Drug Class
Infection is the most discussed safety concern with biologics, and the risk varies meaningfully depending on which class you take. A large study of older adults with psoriatic disease found that the serious infection rate for TNF inhibitors was 2.2 events per 100 person-years, while newer biologics targeting IL-12, IL-23, or IL-17 had a lower rate of 1.4 per 100 person-years. For context, methotrexate, one of the most commonly used older systemic treatments, came in at 2.7 per 100 person-years.
That same analysis found that the newer biologics were associated with a statistically significant 35% lower risk of serious infection compared to the baseline, while TNF inhibitors and methotrexate showed no significant difference from each other. The oral drug tofacitinib (a JAK inhibitor, not a biologic) had a notably higher infection rate of 8.9 per 100 person-years.
Among TNF inhibitors specifically, not all carry the same risk. A comprehensive meta-analysis found that certolizumab pegol had the highest ranking for serious infections, while etanercept ranked lowest. TNF inhibitors as a class roughly double the risk of tuberculosis reactivation, which is why TB screening before starting treatment is standard practice.
Injection Site Reactions
If you’re self-injecting a biologic at home, injection site reactions are the side effect you’re most likely to notice. These typically involve redness, itching, or mild pain where the needle went in. In a retrospective study of 141 psoriasis patients on biologics, the rates varied widely by drug: ixekizumab caused reactions in 55% of patients, guselkumab in about 14%, adalimumab in 9%, and risankizumab in 7%. Two other common biologics, ustekinumab and secukinumab, caused zero reactions in that study.
The good news is that these reactions are mild. More than half appeared within an hour of injection, the most common symptom was simple redness, and no patient in the study needed medical treatment. Symptoms typically resolved on their own within a few days. Rotating your injection sites, injecting slowly, and letting the medication warm to room temperature beforehand all help reduce the likelihood.
Skin Cancer Risk
Because biologics modify immune function, there’s been concern about whether they increase cancer risk over time. A meta-analysis covering nearly 13,740 patients found that the incidence rate of melanoma among biologic users was 0.08 per 100 person-years, compared to an estimated 0.02 per 100 persons in the general population. For non-melanoma skin cancers, the rate was 0.45 per 100 person-years versus 0.08 in the general population.
These numbers are higher than background rates, but it’s important to note that psoriasis itself is associated with increased skin cancer risk, partly because many patients have a history of UV-based treatments like phototherapy. The follow-up periods in most studies have also been relatively short, making it hard to draw firm conclusions about long-term risk. Your dermatologist will typically screen for non-melanoma skin cancers at follow-up visits, especially if you have additional risk factors like fair skin or a history of sun damage.
Cardiovascular Considerations
Psoriasis itself is an independent risk factor for heart attack and stroke, largely because chronic inflammation accelerates the process that clogs arteries. This creates a complicated picture when evaluating cardiovascular safety of biologics: the drugs could theoretically reduce cardiovascular risk by lowering systemic inflammation, or they could introduce new risks through immune modulation.
A 19-year analysis of FDA adverse event reports identified 4,206 major cardiovascular events (heart attacks, strokes, and cardiovascular deaths) among psoriasis patients on biologics. Among those reports, TNF inhibitors accounted for the largest share, though they’ve also been on the market the longest with the most users. IL-23 inhibitors, the newest class, had the fewest reported events (194 total), partly reflecting their shorter time on the market and smaller patient base.
This type of data captures signals worth watching but can’t prove that biologics caused these events. Many psoriasis patients already have elevated cardiovascular risk from obesity, diabetes, or smoking, making it difficult to separate the drug’s effect from the disease’s effect. The takeaway is that cardiovascular health should be part of the conversation with your doctor, particularly if you already have risk factors.
What Screening Happens Before You Start
Before prescribing a biologic, your dermatologist will order a round of baseline lab work. According to American Academy of Dermatology guidelines, this typically includes a complete blood count, a comprehensive metabolic panel (which checks liver and kidney function), tuberculosis testing, and screening for hepatitis B and C. HIV testing may be added depending on your history.
TB screening is particularly important because TNF inhibitors can reactivate latent tuberculosis that’s been silently present for years. If your TB test comes back positive, you won’t necessarily be disqualified from biologics, but you’ll need a chest X-ray or CT scan to rule out active disease, and you may need to start TB treatment before beginning the biologic.
Ongoing Monitoring While on Treatment
Once you’re on a biologic, follow-up visits typically happen quarterly to yearly depending on how you’re responding and tolerating the medication. At these visits, your doctor will assess for signs of infection, check for skin cancers if you have risk factors, and may repeat TB screening annually. The monitoring schedule tends to be lighter than what’s required for older systemic drugs like methotrexate, which demands regular liver function tests because of its potential for liver toxicity.
Most biologics are dosed every few weeks to every few months after an initial loading period, so the treatment itself is relatively low-maintenance compared to daily pills or frequent lab draws. Many patients self-inject at home and only visit the clinic for routine check-ins, which is a practical advantage that contributes to long-term adherence.
How Newer Biologics Compare to Older Ones
The trend in biologic development has been toward greater precision, and the safety data reflects that. IL-23 inhibitors, the newest class, target a narrower piece of the immune system than TNF inhibitors, which were the first biologics approved for psoriasis. This shows up in the infection data: newer biologics have lower serious infection rates than both TNF inhibitors and traditional systemic drugs like methotrexate.
IL-17 inhibitors sit somewhere in the middle. They’re highly effective for skin clearance but carry a unique risk of inflammatory bowel disease flares, so they’re generally avoided in people with a history of Crohn’s disease or ulcerative colitis. They also modestly increase the risk of fungal infections, particularly candidiasis, because IL-17 plays a specific role in antifungal defense.
No biologic is risk-free, but the overall picture is reassuring. For moderate to severe psoriasis, the risks of untreated disease (which include joint damage, cardiovascular disease, depression, and significantly impaired quality of life) generally outweigh the risks of treatment. The key is matching the right biologic to your health profile, which is why the screening and monitoring process exists.