Short answer: Low blood sugar (hypoglycemia) is the most common Fiasp side effect, as with all insulin. In the label's adult type 1 trial, nasopharyngitis affected 20.2% to 23.9% and upper respiratory infection 7.4% to 9.1%. In type 2, urinary tract infection affected 5.9%. Severe low blood sugar ranged from 1.1% to 8.0% across studies. Fiasp has no boxed warning.
What Fiasp is approved for: Fiasp is a rapid-acting mealtime insulin approved to improve blood sugar control in adults and children with diabetes (section 1).
Source
FIASP (insulin aspart) injection, for subcutaneous or intravenous use, prescribing information and Patient Information. Novo Nordisk. DailyMed, version published July 25, 2023. DailyMed setid 834e7efc-393f-4c55-9125-628562a8a5cf
No. The current Fiasp label has no boxed warning.
These are the label's own numbers from the Adverse Reactions section. Where the label compares with placebo (a dummy treatment), both columns are shown, so you can see how much more often a reaction happened on Fiasp.
| Adverse reaction | Mealtime FIASP + insulin detemir, % (N=386) | Postmeal FIASP + insulin detemir, % (N=377) |
|---|---|---|
| Nasopharyngitis | 20.2 | 23.9 |
| Upper respiratory tract infection | 9.1 | 7.4 |
| Nausea | 4.9 | 5.0 |
| Diarrhea | 5.4 | 3.2 |
| Back pain | 5.2 | 4.0 |
Incidence 5% or more and at the same rate or greater with Fiasp than comparator. Both columns are Fiasp, taken at the start of a meal or after the meal, with insulin detemir. Mean exposure was 25 weeks.
| Adverse reaction | FIASP + insulin glargine, % (N=341) |
|---|---|
| Urinary tract infection | 5.9 |
Fiasp with insulin glargine; the table has one Fiasp column. Mean exposure was 24 weeks.
| Adverse reaction | Mealtime FIASP + insulin degludec, % (N=261) | Postmeal FIASP + insulin degludec, % (N=258) |
|---|---|---|
| Viral upper respiratory tract infection | 23.0 | 20.5 |
| Upper respiratory tract infection | 8.4 | 12.4 |
| Influenza | 7.7 | 5.8 |
| Rhinitis | 3.8 | 6.2 |
| Headache | 6.1 | 10.1 |
| Pyrexia | 8.4 | 6.2 |
| Vomiting | 3.4 | 8.1 |
Children with type 1 diabetes, mean age 11.7 years, Fiasp at mealtime or after the meal with insulin degludec. Mean exposure was 26 weeks.
| Study and group | Severe hypoglycemia, % |
|---|---|
| Study A, type 1 adults, mealtime FIASP + insulin detemir (N=386) | 6.7 |
| Study A, type 1 adults, postmeal FIASP + insulin detemir (N=377) | 8.0 |
| Study B, type 2 adults, FIASP + insulin glargine (N=341) | 3.2 |
| Study E, type 1 children, mealtime FIASP + insulin degludec (N=261) | 1.1 |
| Study E, type 1 children, postmeal FIASP + insulin degludec (N=258) | 3.1 |
| Study D, type 1 adults on a pump, FIASP (N=236) | 4.7 |
Severe meant an episode needing another person to give carbohydrate, glucagon or other resuscitative help. Study D used an insulin pump.
Whole-body allergic reactions (generalized skin rash and facial swelling) were reported in 0.4% of adults. Allergic skin reactions such as eczema, rash, itchy rash, hives and dermatitis were reported in 1.7% of adults. In the pump study, allergic reactions were reported in 4.2% of adults; in the children's study, 4%.
Injection site reactions occurred in 1.6% of adults overall and 2.2% in Study A; infusion site reactions in 10.2% of adults on a pump (Study D); injection site reactions in 4.2% of children (Study E).
Lipodystrophy (skin pits or thickening at injection sites) was reported in 0.4% of adults and 2.1% of children. Peripheral swelling (edema) occurred in 0.8% of adults.
Average weight gain was 0.7 kg in adults with type 1 diabetes (Study A) and 2.7 kg in adults with type 2 diabetes (Study B).
On a pump, adults on Fiasp reported more confirmed low blood sugar within the first hour after a meal than on NovoLog. Children on Fiasp reported more confirmed lows than on NovoLog, more so at night.
Reported after approval: localized cutaneous amyloidosis (lumps under the skin) at injection sites. Injecting into those lumps has raised blood sugar, and a sudden switch to normal skin has lowered it.
The Warnings and Precautions part of the label lists these. Each line gives the label's heading and what it means in plain words.
Who should not use it. Fiasp is not used during an episode of low blood sugar, or by people allergic to insulin aspart or any of its ingredients.
Never share a pen or cartridge. A FlexTouch pen, PenFill cartridge or cartridge device is never shared, even if the needle is changed, and vial users never share needles or syringes, because of the risk of passing on blood-borne infections.
Changes in insulin regimen. Changing insulin strength, maker, type, injection site or method can cause high or low blood sugar, so changes are made under close medical supervision with more glucose checks.
Low blood sugar. Hypoglycemia is the most common reaction to any insulin. Severe episodes can cause seizures, unconsciousness or death, and can affect driving. Awareness of lows may be reduced with long diabetes, nerve damage, beta-blockers or repeated lows. Kidney or liver problems can raise the risk.
Medication mix-ups. Mix-ups between insulin products have been reported, so the insulin label is checked before each injection.
Low potassium. All insulins shift potassium into cells and can cause low potassium, which untreated can cause breathing paralysis, heart rhythm problems and death.
Serious allergic reactions. Severe, life-threatening whole-body allergy, including anaphylaxis, can occur; Fiasp is stopped if it does.
Heart failure with TZDs. Thiazolidinediones (such as pioglitazone) with insulin can cause fluid retention that may lead to or worsen heart failure.
Insulin pump failure. A pump or infusion set malfunction can quickly lead to high blood sugar and ketoacidosis. Pump users are trained to give insulin by injection and keep backup insulin on hand.
From the Patient Information that comes with Fiasp:
Dose Track has a side-effect log. Each entry records the symptom, a severity (none, mild, moderate, severe or life-threatening), the date and an optional note, and can be tied to a specific dose or logged on its own. The history screen shows what you logged over time, which makes it easier to tell your prescriber when a reaction started and whether it is easing. The app records what you enter; it does not judge whether a symptom is serious. For anything on the label's call-your-doctor list, call your doctor.
This page is what the FDA label says, in plain words. It is not medical advice. Follow your prescriber, and ask them or your pharmacist about anything here.