Short answer: Low blood sugar (hypoglycemia) is the most common NovoLog Mix 70/30 side effect. In the label's 3-month trial, hypoglycemia affected 69% with type 1 and 47% with type 2 diabetes, and severe lows 16% and 4%. Headache affected 35% in type 1, and upper respiratory infection 12% in type 2. The trial had no placebo group. NovoLog Mix 70/30 has no boxed warning.
What NovoLog Mix 70/30 is approved for: NovoLog Mix 70/30 is a premixed insulin approved to improve blood sugar control in adults with diabetes. It is not recommended for diabetic ketoacidosis, and its fixed proportions do not allow separate basal and mealtime dose changes (section 1).
Source
NOVOLOG MIX 70/30 (insulin aspart protamine and insulin aspart) injectable suspension, for subcutaneous use, prescribing information and Patient Information. Novo Nordisk. DailyMed, version published September 30, 2026. DailyMed setid 1861fcee-7673-4afe-a206-08fa05c0add2
No. The current NovoLog Mix 70/30 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 NovoLog Mix 70/30.
| Preferred term | N (n=55) | % |
|---|---|---|
| Hypoglycemia | 38 | 69 |
| Headache | 19 | 35 |
| Influenza-like symptoms | 7 | 13 |
| Dyspepsia | 5 | 9 |
| Back pain | 4 | 7 |
| Diarrhea | 4 | 7 |
| Pharyngitis | 4 | 7 |
| Rhinitis | 3 | 5 |
| Skeletal pain | 3 | 5 |
| Upper respiratory tract infection | 3 | 5 |
A 3-month open-label trial with doses before breakfast and before supper. There was no placebo or comparator column.
| Preferred term | N (n=85) | % |
|---|---|---|
| Hypoglycemia | 40 | 47 |
| Upper respiratory tract infection | 10 | 12 |
| Headache | 8 | 9 |
| Diarrhea | 7 | 8 |
| Neuropathy | 7 | 8 |
| Pharyngitis | 5 | 6 |
| Abdominal pain | 4 | 5 |
| Rhinitis | 4 | 5 |
Same 3-month trial, type 2 diabetes. There was no placebo or comparator column.
Severe low blood sugar, needing another person's help, IV glucose or glucagon, affected 16% of adults with type 1 and 4% with type 2 diabetes at 12 weeks. The label warns that comparing these rates with other products may be misleading.
Redness, swelling or itching at the injection site usually clears in a few days to a few weeks, but has sometimes required stopping NovoLog Mix 70/30. Severe whole-body allergy (anaphylaxis) has been reported.
Fast improvement in blood sugar control has been linked to a temporary change in eye focus, worsening diabetic eye disease and painful nerve symptoms. Skin pits or thickening, weight gain and swelling from sodium retention can also occur.
In a 3-month study with an extension in type 2 adults, 100% tested positive for anti-insulin antibodies at least once in the first 12 months (91.4% already at baseline), and 91.4% for anti-drug antibodies (62.1% at baseline). The label says these did not worsen control or require more insulin.
Reported after approval: other insulins given by mistake in place of NovoLog Mix 70/30, and localized cutaneous amyloidosis (lumps under the skin) at injection sites with insulin aspart.
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. NovoLog Mix 70/30 is not used during an episode of low blood sugar, or by people allergic to it or one of its inactive ingredients.
Never share a pen or syringe. A FlexPen 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. In type 2 diabetes, other diabetes medicines may need adjusting.
Low blood sugar. Hypoglycemia is the most common reaction to all insulins. 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.
Serious allergic reactions. Severe, life-threatening whole-body allergy, including anaphylaxis, can occur; NovoLog Mix 70/30 is stopped if it does.
Low potassium. All insulins shift potassium into cells and can cause low potassium, which untreated can cause breathing paralysis, heart rhythm problems and death.
Heart failure with TZDs. Thiazolidinediones (such as pioglitazone) with insulin can cause fluid retention that may lead to or worsen heart failure.
From the Patient Information that comes with NovoLog Mix 70/30:
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.