L-lysine side effects in cats

84 reports sent to the FDA between 2012 and 2026 involve L-lysine in cats. The most reported problems were vomiting, loss of appetite, lethargy. 38% were marked serious.

84Reports
38%Marked serious
0.0%Only medicine involved
32%Recovered
9.5%Died or euthanised
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About this medicine

Type: medicine.

Most reported side effects

24 29%
Loss of appetite
19 23%
Lethargy
16 19%
Ocular discharge
11 13%
Hair loss
11 13%
Blood problems
9 11%
Breathing problems
9 11%
Liver problems
8 9.5%
Weight loss
8 9.5%
Behaviour change
8 9.5%
Itching
8 9.5%
Application site reaction
8 9.5%
Fever
8 9.5%
Diarrhea
7 8.3%
Kidney problems
7 8.3%

Share = percentage of this medicine's reports that mention the problem. One report can list several problems.

Reports that it didn't work

Some reports are about the medicine not working (for example a cat still getting fleas or heartworm), not about a side effect.

Didn't work as expected
4 4.8%
Didn't stop fleas
3 3.6%
Didn't stop worms
2 2.4%

How soon problems started

Same day
18 29%
1–2 days
12 19%
3–7 days
4 6.5%
1–4 weeks
6 9.7%
Over a month
22 35%

Time from the first dose to the first sign, where both dates were reported (62 reports).

How the animals did

Recovered
25 30%
Recovered with lasting effects
2 2.4%
Still unwell when reported
29 35%
Died
5 6.0%
Euthanised
3 3.6%
Not known
20 24%

Breeds named most often

Popular breeds appear more often because there are more of them.

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