What each label records
The US prescribing information does not include dizziness in its Table 1, which only lists reactions seen in at least 5% of people in the placebo-controlled trials. It appears in section 6.2, a list of reports received after approval from a population of unknown size, where a rate cannot be estimated. [1] The European summary of product characteristics, which draws on the phase 3a trials, LEADER and spontaneous reports, puts dizziness in its common class. [2] The Canadian monograph prints the individual trials, counting every event reported by at least 1% of people regardless of cause, and also mentions fainting among less common trial events. [3]
| Source and term | Victoza® 0.6 mg | 1.2 mg | 1.8 mg | Comparison group |
|---|---|---|---|---|
| US label, section 6.2 (postmarketing) [1] | Reported, no rate | — | ||
| Canada, LEAD-2 (with metformin): dizziness [3] | 2.1% | 2.9% | 2.1% | Placebo 0.8%; glimepiride 0.8% |
| Canada, LEAD-2: vertigo [3] | 0.4% | 0.4% | 1.2% | Placebo 0.0%; glimepiride 0.8% |
| Canada, LEAD-5 (with metformin and glimepiride): dizziness [3] | — | — | 1.3% | Placebo 1.8%; insulin glargine 0.4% |
| Canada, trial 1860 (with metformin): dizziness [3] | — | 3.6% | 4.1% | Sitagliptin 2.7% |
| Canada, LEAD-3 (52 weeks, alone): dizziness (events over 5%) [3] | — | 5.2% | 6.5% | Glimepiride 5.2% |
| EU SmPC, Table 1 [2] | Common (1 in 100 to 1 in 10) |
What the rows suggest
Against placebo, dizziness was more frequent on Victoza® in LEAD-2 but not in LEAD-5, where people also took a sulfonylurea. [3] Against other diabetes medicines the gap narrows: in the year-long LEAD-3 trial, 6.5% on 1.8 mg and 5.2% on 1.2 mg reported dizziness, the same 5.2% as on glimepiride. [3] There is no steady rise with dose. Taken together, the figures fit the European label’s common rating without suggesting that dizziness is one of the main reactions to Victoza®. [2][3]
At 3 mg a day, the dose sold for weight management as Saxenda®, dizziness was reported by 6.9% of adults against 5% on placebo, and by 10.4% of adolescents against 3.2%. [4] Its label adds that dizziness was reported mostly in the first 12 weeks, often together with stomach side effects. [4] Those numbers come from a different product and population and do not describe Victoza®.
Heart rate and blood pressure
This is where Victoza®’s information differs from many weight-loss labels. The US label says Victoza® did not affect blood pressure adversely and that average heart rate rose by 2 to 3 beats per minute compared with placebo. [1] In LEADER, systolic pressure fell slightly more on Victoza® than placebo (1.4 against 0.2 mmHg) after three years, while diastolic pressure fell slightly less. [3] So a large drop in blood pressure is not a feature of this label.
The Canadian monograph goes further on rhythm. In pooled phase 3a trials, a combined group of fast heart rhythm events occurred in 0.7% on liraglutide, 0.2% on placebo and 0.7% on other medicines, with extra beats the most common. [3] Its patient information explains that, rarely, medicines that raise heart rate or prolong the PR interval can cause rhythm changes leading to dizziness, palpitations or fainting, and that these are more likely with existing heart disease or certain other medicines. [3] In LEADER, the share of people with rhythm-related adverse events was similar on Victoza® and placebo. [3]
Low blood sugar, fluids and allergy
- Low blood sugar. The Medication Guide puts dizziness or light-headedness first among its signs. [1] The risk is higher with a sulfonylurea or insulin, and in patients aged 10 and older whatever else they take. [1] EU product information notes that low blood sugar while driving is the main concern, especially with a sulfonylurea or insulin. [2]
- Fluid loss. The label warns that nausea, vomiting and diarrhea can dehydrate you and harm the kidneys, especially when starting or raising the dose. [1] MedlinePlus counts dizziness or light-headedness among signs of severe dehydration. [8]
- Allergic reaction. The Medication Guide asks you to stop Victoza® and get medical help at once if fainting or dizziness arrives together with a swollen face, lips, tongue or throat, difficulty breathing or swallowing, a very rapid heartbeat or a severe rash. [1]
Beyond the label
An analysis of US spontaneous reports for six GLP-1 medicines, including liraglutide, identified dizziness and presyncope, the feeling of being about to faint, among nervous system signals. Reports of this kind show that people linked a symptom to a medicine; they cannot give a rate or show cause. [5] No liraglutide-specific study of dizziness in type 2 diabetes was found beyond the trial tables above.
Light-headed or spinning: other explanations
MedlinePlus separates two experiences: light-headedness, the sense that you might pass out, and vertigo, the sense that you or the room are moving. [6] Most causes are not serious. Light-headedness is linked to too little blood reaching the brain for a moment, for example after a sudden fall in blood pressure, dehydration, or standing up quickly, and also to flu, colds, allergies, low blood sugar and medicines that lower blood pressure. [6] Vertigo more often comes from the inner ear: positional vertigo, a viral inner-ear infection or Ménière disease. [6]
Heart rhythm problems, stroke and internal bleeding are rarer but serious causes; they usually bring other symptoms such as chest pain, a racing heart, or trouble with speech or vision. [6]
What helps, according to the sources
For light-headedness on standing, MedlinePlus describes avoiding sudden changes of position, sitting for a moment before getting up from lying down, and having something to hold. During vertigo it describes keeping still, building activity back slowly, avoiding bright screens and reading, and not driving, climbing or using heavy machinery until a week after symptoms stop. [6] Canada’s monograph says simply not to drive or operate machinery if you feel dizzy. [3]
The Victoza® Medication Guide asks you to drink fluids to reduce the chance of dehydration and to agree a plan for low blood sugar with your provider before starting, particularly if you use insulin or a sulfonylurea. [1] If your meter shows a low reading, MedlinePlus describes treating it with a sugary drink, food or glucose tablets as your provider has taught you. [7]
Victoza® and Saxenda® are registered trademarks of Novo Nordisk A/S. PepLabo is not affiliated with or endorsed by Novo Nordisk A/S.
When to get help
| Sign | Who to contact | How fast | Source |
|---|---|---|---|
| Dizziness with chest pain, an irregular or racing heartbeat, shortness of breath, weakness, trouble moving an arm or leg, or a change in speech or vision | Emergency services (911 or local number) | Emergency | MedlinePlus [6]; Canadian patient information [3] |
| Fainting or dizziness together with a swollen face, lips or throat, or difficulty breathing or swallowing | Stop Victoza® and get emergency help | Emergency | Medication Guide [1] |
| Low blood sugar signs that do not improve after a sugary snack, or someone who becomes less alert | Emergency services; do not drive yourself | Emergency | MedlinePlus [7] |
| Dizziness with shakiness, sweating, hunger or blurred vision, especially on insulin or a sulfonylurea | Check and treat per your low blood sugar plan; tell your prescriber | Today | Medication Guide [1] |
| Dizziness with vomiting or diarrhea that does not stop, or trouble keeping fluids down | Your prescriber, the same day | Today | Medication Guide [1]; MedlinePlus [6] |
| Dizziness for the first time, new or worsening dizziness, or dizziness after starting a medicine | Contact your health care provider | At your next appointment | MedlinePlus [6] |
