Most Tremfya side effects are mild and last a few days to a few weeks after each injection. The most common reactions, like soreness at the injection site, headache, and fatigue, tend to resolve on their own without needing to stop treatment. How long a side effect lasts depends on which one you’re experiencing, so here’s what to expect for each.
Injection Site Reactions
Redness, swelling, bruising, itching, or pain at the injection site is one of the most frequently reported side effects. In clinical trials, about 1% of patients on the standard 100 mg dose experienced these reactions. They typically show up within hours to a couple of days after the injection and clear up within a few days for most people. Applying a cold compress and avoiding rubbing the area can help.
In rare cases, a more significant skin reaction can develop. One documented case involved a large, itchy, swollen plaque appearing two days after the first injection, with reactions becoming faster and more intense after subsequent doses. That episode took about 10 days to fully resolve with antihistamines and a topical steroid. This kind of delayed hypersensitivity reaction is uncommon, but if your injection site reaction spreads, blisters, or worsens with each dose, it’s worth flagging for your prescriber.
Cold-Like Symptoms
Upper respiratory infections, including sore throat, runny nose, and sinus congestion, are the single most common side effect. In psoriasis trials, about 14% of patients on Tremfya reported these symptoms, compared to roughly 13% on placebo, so the drug only slightly increases the risk beyond what you’d expect normally. These infections were universally mild to moderate and didn’t cause anyone in trials to stop treatment.
Because Tremfya works by dialing down part of your immune system (specifically, it blocks a protein called IL-23 that drives inflammation), you may be slightly more susceptible to catching everyday bugs. A typical cold or sinus infection runs its usual course of one to two weeks. If you notice fever, shortness of breath, or a cough that produces blood, those are signs of something more serious that needs prompt medical attention.
Headache, Joint Pain, and Fatigue
Headache, joint pain, and unusual tiredness are all listed among Tremfya’s common side effects. These are generally temporary, lasting a few days to a few weeks after an injection. Some people notice them most in the first day or two following their dose, with symptoms fading well before the next scheduled injection.
For psoriasis, Tremfya is given at weeks 0 and 4, then every 8 weeks after that. If you notice these side effects clustering right after each injection and resolving within a week or so, that pattern is typical. If headaches, fatigue, or joint pain persist throughout the entire dosing cycle or get progressively worse, that’s a different situation worth discussing with your doctor.
Liver Enzyme Changes
A small percentage of patients see mild elevations in liver enzymes during treatment. In psoriasis trials, this happened in about 2.6% of patients on Tremfya versus 1.9% on placebo. In psoriatic arthritis studies, the rate was higher, around 9%. The important detail: these elevations were self-limited, meaning they resolved on their own even as patients continued treatment. None were associated with symptoms like jaundice, and none required stopping the drug.
You won’t feel liver enzyme changes directly, which is why your doctor may order periodic blood work. Symptoms that could signal a liver problem include yellowing of the skin or eyes, dark urine, nausea, stomach pain, or unexplained loss of appetite.
How Long Tremfya Stays in Your Body
If you stop Tremfya entirely, the medication doesn’t leave your system overnight. Like most biologic drugs, it has a long elimination period. As an antibody-based medication, it takes several weeks to be fully cleared. This means that any side effects linked directly to the drug’s mechanism could potentially linger for a period after your last injection, though most people find that common side effects like injection site reactions and post-dose fatigue stop recurring once they stop injecting.
Long-Term Side Effect Patterns
One reassuring finding from long-term data: side effects don’t appear to accumulate or worsen over time. A pooled safety analysis followed nearly 2,900 patients on Tremfya for up to five years, totaling over 8,600 patient-years of exposure. The rates of side effects, infections, and serious events were either comparable to or lower than what was seen during the initial placebo-controlled period. In other words, the side effect profile at year five looked the same as, or better than, the profile at month four.
Rates of serious infections stayed low at about 0.9 per 100 patient-years, and the rate of side effects leading patients to stop treatment dropped to 1.6 per 100 patient-years over the long term, down from 5.0 during the initial study period. This suggests that people who tolerate the drug well early on tend to continue tolerating it well.
Signs That Need Immediate Attention
Most side effects are manageable, but a few warrant fast action. Signs of a serious allergic reaction include swelling of the face, lips, tongue, or throat, difficulty breathing, chest tightness, dizziness, or widespread hives. These can happen shortly after injection and require emergency care.
Signs of a significant infection, such as fever with chills, painful or warm skin sores, burning during urination, or persistent diarrhea with stomach pain, should be reported to your prescriber promptly rather than waiting for your next appointment. Tremfya’s immune-modulating effects mean infections can occasionally progress faster than they otherwise would.