(It’s Sunday, and you know I have time to (love to) rant.) 
)
Frankly, I’m getting tired of reading responses that parrot a misinterpreted study that is often not meaningful, relevant, or just plain clickbait. Anecdotal reports of negative effects are just that, not a scientific fact. It is easy to see from the many negative reports that the particular supplement use reported in the forum can be attributed to coincidence or other confounding factors. Every time you read an anecdotal report, good or bad, including one from me, it is basically just a personal observation, not a scientific fact, not unlike telling you that a certain food tastes good or bad or that it gives you an upset stomach.
As someone who has researched the effects of low-dose lithium supplements at doses below 20 mg of elemental lithium for decades, regarding their life extension and mental health,
For God’s sake, get it through your heads, PhD, MD, or layman. Less than 20 mg of elemental lithium daily is safe except for a very small percentage of outliers. This is far below the therapeutic doses of lithium prescribed by doctors.
"It is most commonly prescribed as lithium carbonate
The therapeutic range for most indications is 0.4–0.8 mmol/L (12-h post-dose sampling), typically requiring a dose for adults between 400 and 1200 mg daily, individualised according to age, sex, weight, and, importantly, renal function."
Personally, I have taken lithium orotate at 5 to 20 mg of elemental lithium orotate daily for close to 30 years, with nothing but positive effects.
If you throw away your supplement or drug every time you read something negative about it from a forum member, you are not thinking for yourself or doing any of your own research.
Is there any primary evidence of harm below 20 mg of elemental lithium that supplementation causes harm in a statistically meaningful way?
Bottom line first:
No. Across:
A formal preclinical toxicology battery (Murbach 2021) — no harm
A systematic review of 16 interventional studies (Strawbridge 2023) — unanimous safety
The only controlled human dosing study at 5 mg/day (Smith 2024) — no AEs
Decades of post-market surveillance — no published safety signal
Population-level natural-exposure studies — protective associations, not harm
There is no primary evidence of statistically meaningful harm from daily lithium orotate or aspartate supplementation delivering under ~20 mg of elemental lithium. Every controlled study, every preclinical toxicology study, and decades of post-market surveillance have failed to produce a clear safety signal at this dose range. The one published case of “toxicity” at low-ish doses involved someone who deliberately took 18 capsules at once. The evidence base is thin, mostly short-term, and almost entirely uncontrolled. A recent self-selected user survey found subjectively reported side effects were “more prevalent than anticipated,” but without a control arm those numbers have no anchor.
Primary evidence on safety <20 mg elemental Li
1. Strawbridge et al. 2023 — Systematic review of low-dose lithium interventional studies
This is the most rigorous synthesis available. It pooled 16 interventional studies of low-dose lithium across neuropsychiatric outcomes. Of the 16 included studies, reports were unanimous on the safety of low-dose lithium across all studied populations PubMed Central, and the authors concluded that low-dose lithium is safe and may improve cognition as well as affective symptoms ScienceDirect. The accompanying narrative review noted there is a paucity of research into adverse effects of low-dose lithium, although one as-yet unpublished study found increased (though clearly non-significant) CKD rates in people with serum lithium levels of 0.3–0.59 PubMed Central — well above what supplements produce.
2. Murbach et al. 2021 — Formal toxicological evaluation of lithium orotate
The most direct safety study ever done on the compound. In a 28-day, repeated-dose oral toxicity study, rats were administered 0, 100, 200, or 400 mg/kg body weight/day of lithium orotate by gavage. No toxicity or target organs were identified; therefore, a no observed adverse effect level was determined as 400 mg/kg body weight/day. These results are supportive of the lack of a postmarket safety signal from several decades of human consumption. ScienceDirect The compound also was not mutagenic or clastogenic in bacterial reverse mutation and in vitro mammalian chromosomal aberration tests, and did not exhibit in vivo genotoxicity in a micronucleus test in mice ScienceDirect.
That 400 mg/kg/day NOAEL in rats translates to roughly 27,000 mg of lithium orotate daily for a 70 kg human — about 225× the typical 120 mg supplemental dose.
URL: https://www.sciencedirect.com/science/article/pii/S0273230021001136
3. Pacholko & Bekar 2022 — Direct head-to-head animal comparison
Re-ran the historically-cited Smith & Schou (1979) toxicity experiment that scared researchers away from orotate for 40 years. Concluded that lithium orotate has a safer kidney profile than lithium carbonate, and that both increased TSH only in females, but the increase was lower in the orotate group Wikipedia. The original 1979 study used what the original authors later acknowledged were toxic-range doses.
URL: https://pmc.ncbi.nlm.nih.gov/articles/PMC8413749/