Short answer: In the label's type 1 diabetes trials, the most common Symlin side effects were nausea (48% vs 17% on placebo), poor appetite (17% vs 2%), injuries (14% vs 10%) and vomiting (11% vs 7%). In type 2 diabetes on insulin, nausea was 28% vs 12% and headache 13% vs 7%. Symlin has a boxed warning for severe low blood sugar when used with insulin.
What Symlin is approved for: Symlin is approved as an add-on treatment for people with type 1 or type 2 diabetes who use mealtime insulin and have not reached their glucose goals despite optimal insulin therapy (section 1).
Source
SYMLINPEN (pramlintide acetate) injection, prescribing information and Medication Guide. AstraZeneca. DailyMed, version published August 20, 2024. DailyMed setid 4aea30ff-eb0d-45c1-b114-3127966328ff
WARNING: SEVERE HYPOGLYCEMIA
Using Symlin with insulin raises the risk of severe low blood sugar, especially in type 1 diabetes. When it happens, it is seen within 3 hours after a Symlin injection. Serious injuries can happen if it occurs while driving, using heavy machinery or doing other high-risk activities. The label says careful patient selection, careful instruction and lowering the insulin dose are critical to reduce this risk.
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 Symlin.
| Adverse reaction | Symlin 30 or 60 mcg 3 times daily + insulin (N=716) % | Placebo + insulin (N=538) % |
|---|---|---|
| Nausea | 48 | 17 |
| Anorexia | 17 | 2 |
| Inflicted Injury | 14 | 10 |
| Vomiting | 11 | 7 |
| Arthralgia | 7 | 5 |
| Fatigue | 7 | 4 |
| Allergic Reaction | 6 | 5 |
| Dizziness | 5 | 4 |
Long-term placebo-controlled trials; Symlin 30 or 60 mcg three times daily with insulin. Inflicted injury includes abrasions, bruises, burns, fractures, cuts and muscle strains. Hypoglycemia is reported separately.
| Adverse reaction | Symlin 120 mcg 2 times daily + insulin (N=292) % | Placebo + insulin (N=284) % |
|---|---|---|
| Nausea | 28 | 12 |
| Headache | 13 | 7 |
| Anorexia | 9 | 2 |
| Vomiting | 8 | 4 |
| Abdominal pain | 8 | 7 |
| Dizziness | 6 | 4 |
| Cough | 6 | 4 |
| Pharyngitis | 5 | 2 |
Symlin 120 mcg twice daily with insulin.
Severe low blood sugar needing another person's help, type 1 diabetes, first 3 months (trials without an insulin cut at the start): 16.8% on Symlin plus insulin vs 10.8% on placebo plus insulin. Needing medical help: 7.3% vs 3.3%.
In the type 1 dose-titration study, where insulin was reduced at the start, severe low blood sugar in the first 3 months was 13.5% on Symlin vs 6.1% on placebo.
Severe low blood sugar needing another person's help, type 2 diabetes on insulin, first 3 months: 8.2% on Symlin vs 2.1% on placebo; needing medical help 1.7% vs 0.7%.
Redness, swelling or itching at the injection site can happen and usually clears in a few days to a few weeks.
The Warnings and Precautions part of the label lists these. Each line gives the label's heading and what it means in plain words.
Patient selection. The label lists who should not be considered: poor follow-through with insulin or glucose testing, HbA1c over 9%, repeated severe low blood sugar needing help in the past 6 months, low blood sugar unawareness, gastroparesis, drugs that speed gut movement, and children.
Low blood sugar. Symlin alone does not cause low blood sugar, but with mealtime insulin there is a higher risk of severe low blood sugar, especially in type 1 diabetes. Warning signs can be weaker with long-standing diabetes, nerve damage or some blood pressure drugs such as beta-blockers.
Never share a SymlinPen. A SymlinPen must never be shared, even with a new needle, because of the risk of passing on blood-borne infections.
Never mix with insulin. Mixing Symlin and insulin can change how both work, causing poor glucose control or low blood sugar. They are always given as separate injections.
Other oral medicines. Symlin slows stomach emptying and can delay other pills. When a pill needs to work fast, the label says to take it at least 1 hour before or 2 hours after the Symlin injection.
Drugs that affect gut movement. Symlin is not recommended for people taking other medicines that change how fast the gut moves.
Allergy. Injection-site redness, swelling or itching can happen; some of it may be due to other causes such as skin cleaners or poor injection technique.
From the Medication Guide that comes with Symlin:
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.