Safety action / O-037
Adverse effects: what to record and where to report
A useful report starts with a timeline. Record the product, batch, source, symptoms and outcome, then choose the correct UK route.
If you suspect an adverse effect, check urgent symptoms first. Once you are safe, record the product name exactly as shown, batch reference, source, exposure timing, symptom timeline, other medicines and the outcome. Use Yellow Card for a suspected medicine problem and the separate MHRA service for a suspicious online seller.
Check urgent signs first. Call 999 for severe breathing difficulty, mouth or throat swelling, chest pain, collapse, stroke signs, a seizure that does not stop or sudden severe confusion.
The record set that makes a report useful
| Field | What to capture | Why it matters |
|---|---|---|
| Product | Label name, form, stated ingredient and strength. | Different products can share a molecule name. |
| Batch and vial | Batch or lot, serial details, expiry, photographs and seal condition. | Links the event to a traceable presentation. |
| Source | Website, social account, pharmacy, order record and delivery date. | Identifies the supply route and jurisdiction. |
| Timeline | Date and time of exposure, first symptom, progression and recovery. | Lets an assessor examine the temporal relationship. |
| Clinical context | Relevant conditions, prescribed medicines, supplements and care received. | Helps separate competing explanations without asking you to diagnose the cause. |
| Outcome | Ongoing symptoms, tests, treatment, admission or recovery. | Shows seriousness and follow-up. |
Record first, then report
- 1
Check urgent symptoms first
Call 999, attend A&E or use NHS 111 when the symptoms require care.
- 2
Record the event timeline
Write down the product, batch, source, dates, symptoms and clinical outcome.
- 3
Preserve documents
Keep packaging, receipts, seller messages, screenshots and the supplied certificate.
- 4
Choose the official route
Use Yellow Card for a suspected medicine problem and the seller service for possible illegal supply.
Choose the right route
Suspected side effect or product problem
Use the submit a Yellow Card report. The MHRA states that suspicion is enough; you do not need to prove causality.
Possible illegal online supply
Use the MHRA suspicious seller route. It accepts website and social-media reports, including anonymous reports.
Our reporting rule
We keep three records separate: what the person experienced, what the label claimed and what the product evidence established. A report can contain a suspected causal link, but the event description should remain usable even if later testing changes the product identity.
Questions about recording and reporting
What should I record after a suspected peptide reaction?
Record the product and batch, seller, dates, timing of use and symptoms, other medicines or supplements, photographs where safe, medical care received and the outcome. Keep the original wording from labels and documents.
Should I report before seeking medical help?
No. Urgent care comes first. Call 999 or attend A&E for emergency warning signs, or use NHS 111 when you need urgent advice but it is not a life-threatening emergency.
Do I need proof that the product caused the problem?
No. The MHRA accepts reports based on suspicion. Your report should separate what happened from what you think caused it and include enough detail for assessment.
Which route covers an illegal online seller?
Use the MHRA suspicious seller service for possible illegal online supply. Use Yellow Card for suspected side effects, defective medicines and fake healthcare products. A case may justify both routes.
Official reporting sources
- MHRA Yellow Card guidanceAccessed 7 August 2026
- MHRA suspicious online seller serviceAccessed 7 August 2026
- Peptide safety and uncertainty hubAccessed 7 August 2026
Editorial experience
From our work: how we checked this page
For topical-map item O-037, Adverse effects: what to record and where to report was checked as a distinct editorial task, not treated as a generic peptide page. We reviewed 2 unique external sources and 6 internal destinations in the page, then checked that the opening answer, headings, source descriptions and linked next steps stayed within the same claim boundary. The count records links in the published page and is not a claim that every source carries equal evidential weight.
Eleni Kiromitis checked study design, biomedical evidence, evidence directness and laboratory context. Dr Stavroula Nikitopoulou checked clinical claims, adverse effects, contraindications, red flags and patient-facing safety wording. Each reviewer stayed within the remit published on the governance page. Yianni Kiromitis retained responsibility for source verification, editorial decisions and correction management.
We did not use patient experience, a personal treatment outcome, seller testimony or an assumed product identity to support this page. The publication did not independently test a vial for this review. Where a page refers to a laboratory result, that result applies only to the named sample, method and attribute. We kept uncertainty beside the conclusion, recorded which source supports each material claim, and checked that the visible review date matches the publication record. A new controlled study, regulator update, corrected source, analytical report or credible safety signal can trigger reassessment through the public correction route.