The headache row in each document
Section 6.1 of the US label reports headache in all three injection safety tables: an adult 2.4 mg pool of three placebo-controlled trials lasting up to 68 weeks, two 72-week trials with 7.2 mg, 2.4 mg and placebo arms, and a single 68-week trial in young people aged 12 and older. [1] The EU product information pools STEP 1–4, and the Canadian monograph pools STEP 1–3 with migraine counted in the same row. [2][3]
| Source and pool | Placebo | Wegovy® 2.4 mg | Wegovy® 7.2 mg |
|---|---|---|---|
| US Table 3: adults on 2.4 mg, up to 68 weeks [1] | 10% | 14% | — |
| US Table 4: adults in the 7.2 mg trials, 72 weeks [1] | 7% | 8% | 9% |
| US Table 5: adolescents aged 12 and older [1] | 16% | 17% | — |
| EU SmPC 4.8: STEP 1–4 [2] | not given | “very common”, mainly during dose escalation | — |
| Canadian Table 4: STEP 1–3, headache and migraine [3] | 11% | 16% | — |
Placebo groups had headaches too
Headaches are common in daily life, and the placebo columns reflect that. In the first US adult pool, one in ten people on placebo reported a headache, against roughly one in seven on the medicine. In the 7.2 mg trials, the steps from placebo to 2.4 mg to 7.2 mg were one percentage point each, and in teenagers 17% on Wegovy® against 16% on placebo is close to no difference. [1]
The Canadian figure is higher on both sides (16% versus 11%) because migraine is counted together with headache there. [3] Either way, compared with nausea (44% against 16% in adults), the extra share of headache on Wegovy® is small. [1]
On timing, the US label is silent, but the EU product information marks headache with the same footnote it uses for nausea and vomiting: mainly seen while the dose is being stepped up. [2] The injection climbs from 0.25 mg in four-week steps, and a prescriber may delay a step by four weeks if a dose is not tolerated. [1]
What the label links headache to, and what it does not
- Low blood sugar in type 2 diabetes: the Medication Guide includes headache in its list of possible low blood sugar signs, alongside dizziness, sweating, shakiness, hunger, blurred vision, a fast heartbeat and confusion. In a trial of adults with type 2 diabetes, blood sugar below 54 mg/dL was recorded in 6.2% on the injection and 2.5% on placebo, and the risk rose with a sulfonylurea. [1]
- Outside diabetes: the label notes that low blood sugar was not systematically recorded in its weight-reduction trials, although three serious episodes on Wegovy® versus one on placebo were reported in a large heart-outcomes trial in people without diabetes. [1]
- Fluid loss, listed separately: the label warns that vomiting and diarrhoea can cause dehydration, [1] and MedlinePlus lists headache among signs of mild to moderate dehydration. [5] The label itself does not join these two facts, so treat the connection as general background.
- Not explained: none of the documents describes a direct mechanism for headache on semaglutide.
Other common causes of headache
MedlinePlus describes tension headache, linked to tight muscles, stress, anxiety or posture, as the most common type. Migraine tends to throb on one side and can be triggered by certain foods, caffeine withdrawal, lack of sleep and alcohol. Frequent use of pain relievers can itself cause rebound headaches, and colds, flu, fever and premenstrual syndrome can bring headaches too. [4]
Less often, headache signals something serious, such as very high blood pressure, an infection of the brain or its lining, bleeding in the brain, carbon monoxide poisoning or sleep apnoea. [4] A new pattern of headaches deserves its own assessment rather than being put down to the medicine.
Self-care and pain-reliever questions
For migraine and tension headaches, MedlinePlus suggests drinking water, especially after vomiting, resting in a quiet dark room, placing a cool cloth on the head and using relaxation techniques. It also suggests a headache diary: when the pain began, what you ate and drank in the previous 24 hours, how much you slept, what you were doing and what eased it. [4] It advises talking to a provider if you need pain medicines three or more days a week. [4]
On medicines, the Wegovy® label names no pain reliever. Section 7.2 says Wegovy® delays stomach emptying and may affect how oral medicines are absorbed, and the Medication Guide asks you to keep a list of everything you take, including over-the-counter products. [1] The EU product information reports that semaglutide slowed the early absorption of paracetamol after a meal without changing total exposure, and that no paracetamol dose adjustment is needed. [2] Ask your pharmacist which pain reliever fits your other conditions and medicines; Novo Nordisk’s patient page also lists headache among the common side effects to talk over with your healthcare professional. [7]
Wegovy® 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 |
|---|---|---|---|
| A sudden, explosive or “worst ever” headache, or headache with slurred speech, vision change, weakness, confusion or loss of balance | Emergency number or nearest emergency room | Emergency | MedlinePlus [4] |
| Headache with fever, stiff neck, nausea and vomiting, or after a head injury | Medical help right away | Emergency | MedlinePlus [4] |
| Headache with shakiness, sweating, confusion or a racing heart, if you have type 2 diabetes | Follow your low blood sugar plan; contact your diabetes team | Emergency | Medication Guide [1]; MedlinePlus [6] |
| Headache with swelling of the face or throat, severe dizziness or fainting | Stop Wegovy® and get medical help right away | Emergency | Medication Guide [1] |
| Headache that worsens over 24 hours, or new headaches after age 50 | Medical help the same day | Today | MedlinePlus [4] |
| Headaches that keep coming back, or needing pain relievers three or more days a week | Your prescriber or GP at an appointment | At your next appointment | MedlinePlus [4]; Medication Guide [1] |
