Tiredness and weakness in the product documents
The labels separate two related terms. Fatigue means tiredness or lack of energy; asthenia means weakness or loss of strength. Both appear in the adult tables, and fatigue also appears in the teen table. [1][3] Every participant also followed a reduced-calorie diet with activity counselling, which is worth remembering when comparing with placebo. [1]
| Document and term | Saxenda® | Placebo | Note |
|---|---|---|---|
| US label, Table 2, fatigue, adults [1] | 7.5% | 4.6% | Mostly in the first 12 weeks |
| US label, Table 2, asthenia, adults [1] | 2.1% | 0.8% | Weakness or lack of strength |
| Canadian monograph, Table 3, adults [3] | Fatigue 254 (7.5%); asthenia 70 (2.1%) of 3,384 | Fatigue 89 (4.6%); asthenia 15 (0.8%) of 1,941 | Same adult pool |
| US label, Table 3, fatigue, ages 12–17 [1] | 4.8% | 3.2% | One trial, 125 vs 126 teens |
| EU SmPC, Table 4 [2] | Fatigue, asthenia: common; malaise: uncommon | — | Common = 1 to 10 in 100 |
A first-three-months pattern
The US and Canadian labels add a timing note that is unusual for a side effect table: asthenia, fatigue, malaise, taste change and dizziness were mainly reported within the first 12 weeks, and often at the same time as nausea, vomiting or diarrhoea. [1][3] Those weeks include the five-week climb from 0.6 mg to 3 mg a day. [1]
The difference with placebo is modest. About three more adults in every hundred reported fatigue on Saxenda®, and neither fatigue nor weakness was among the main reasons adults stopped treatment. [1] The Medication Guide still includes tiredness in its list of the most common adult side effects. [1]
People with moderate kidney impairment may notice more fatigue together with digestive side effects, according to the Canadian monograph. [3]
What research adds
Saxenda® works by reducing how much you eat. The label states that liraglutide lowers weight through lower calorie intake and does not raise 24-hour energy expenditure. [1] In a five-week study in 49 adults with obesity, liraglutide 3 mg increased fullness, reduced hunger and cut the energy eaten at a test lunch by about 16%. [4] A smaller intake is the intended effect, but in the first weeks it can coincide with feeling flat.
Mood can also affect energy. A pooled analysis of 5,325 people in the liraglutide 3 mg trials found depression reported at the same low rate on liraglutide and placebo, and questionnaire scores improved slightly in both groups. [5] In the teen trial, depression appeared in 4.0% on Saxenda® against 2.4% on placebo. [1]
A 2025 analysis of the US FDA reporting database found a signal for lethargy, alongside dizziness and taste problems, across GLP-1 medicines, with nearly half of neurological reports in the first 30 days. [6] Reports of this kind cannot show cause or frequency.
Label effects that can sap energy
- Fluid loss: diarrhoea, nausea and vomiting can dehydrate you, and MedlinePlus lists dizziness and listlessness among the signs of severe dehydration. The label links dehydration on liraglutide to kidney injury. [1][9]
- Low blood sugar: weakness, drowsiness, shakiness and sweating are among the signs listed in the Medication Guide. The risk is higher in adults with type 2 diabetes on insulin or a sulfonylurea and in teenagers on Saxenda®. [1]
- Poor sleep: insomnia was reported by 2.4% of adults on Saxenda® against 1.7% on placebo, mainly in the first three months. [1][2]
- A faster resting heart rate, raised by 2 to 3 beats per minute on average, which the label asks you to report if you feel your heart racing at rest. [1]
Other reasons you may feel worn out
MedlinePlus lists many everyday and medical causes of fatigue: poor or broken sleep, including sleep apnoea, stress, depression or grief, anaemia or low iron, an underactive or overactive thyroid, diabetes, kidney or liver disease, infections, and medicines such as sedatives, antihistamines, blood pressure tablets and water pills. [7]
It also separates fatigue, a lack of energy and motivation, from drowsiness, the need to sleep. [7] That distinction helps when describing what you feel to your prescriber: the Medication Guide lists drowsiness among the signs of low blood sugar, and MedlinePlus notes that some medicines cause drowsiness. [1][7]
What MedlinePlus suggests
For everyday fatigue, MedlinePlus suggests enough sleep, a balanced diet, drinking water through the day, regular exercise, ways to relax such as yoga or meditation, a manageable schedule, and cutting back on alcohol and nicotine. [7] It warns that stimulants such as caffeine are not an effective fix and can leave you worse when they wear off. [7]
It also advises discussing supplements with your provider rather than starting them on your own, and not stopping or changing any medicine without talking to your provider first. [7] With Saxenda®, the Medication Guide asks you to tell your provider about every medicine and supplement you take, and about any side effect that bothers you or does not go away. [1]
Saxenda® is a registered trademark of Novo Nordisk A/S. PepLabo is not affiliated with or endorsed by Novo Nordisk.
When to get help
| Sign | Who to contact | How fast | Source |
|---|---|---|---|
| Thoughts of harming yourself or of suicide | Your provider right away, or your local emergency number | Emergency | MedlinePlus [7] |
| Weakness with sweating, shakiness, confusion or a fast heartbeat if you take insulin or a sulfonylurea, or are a teen on Saxenda® | Check blood sugar as you were shown; contact your care team | Today | Medication Guide [1]; MedlinePlus [8] |
| Confusion, dizziness, blurred vision or little or no urine | Your provider right away | Today | MedlinePlus [7][9] |
| Recent swelling and weight gain with tiredness | Your provider right away | Today | MedlinePlus [7] |
| Tiredness that continues past the first months, or comes with fever, unplanned weight loss or night sweats | Your prescriber | At your next appointment | MedlinePlus [7]; Medication Guide [1] |
| Feeling low or depressed, or waking many times at night | Your doctor | At your next appointment | MedlinePlus [7] |
