Frequently asked
NAD+ questions, answered from the research
Direct answers to the most-searched NAD+ questions — about infusion, injection, oral precursors, safety and dosing — each drawn from the cited literature.
What is the downside of taking NAD+?
Plain oral NAD+ is poorly absorbed intact, so it may do little, and product purity varies widely [5]. IV and injectable NAD+ is compounded and not FDA-approved; a compounded injectable was subject to a Class I recall for endotoxin [5]. A theoretical concern also exists that boosting NAD+ could support existing cancers [5].
Is it safe to take NAD daily?
In trials, oral precursors were generally well tolerated over 8-12 weeks — NR up to 1000 mg/day showed no adverse-event difference from placebo [4], and NMN raised no safety signal up to 900 mg/day [3]. But these are research findings in specific populations, not a recommendation; daily use is a question for a qualified clinician.
Does NAD cause weight gain?
Human NMN and NR trials have not reported weight gain as a typical effect. A 10-week NMN study (250 mg/day) in prediabetic, postmenopausal women improved muscle insulin sensitivity with no change in body composition [1]. The metabolic data point toward neutral-to-favorable body-weight effects, not weight gain, though endpoints vary by trial.
Does NAD make you look younger?
No trial shows NAD+ or its precursors reverse visible aging. The strongest anti-aging data come from rodents, and a 2025 Nature Metabolism review concluded human efficacy for hard endpoints remains limited [6]. Raising blood NAD+ is demonstrated; reversing how you look is not.
Does NAD help with fertility?
Fertility claims rest mainly on rodent oocyte studies and are not established in controlled human trials. The cited human evidence base centers on blood NAD+ elevation [4][3], metabolism [1] and neurology [7][8], not reproduction. The fertility story is preclinical, not clinical.
Does NAD help with weight loss?
Human precursor trials have not demonstrated weight loss as a reliable outcome. The better-supported metabolic finding is improved muscle insulin sensitivity in one NMN RCT, with no change in body weight [1]. Weight loss is not an established effect in the cited literature.
Do NAD patches work?
Transdermal NAD+ patches are marketed but have little controlled evidence. The bulk of human data are for oral precursors [4][3]; sublingual, intranasal and topical or transdermal routes lack rigorous pharmacokinetic support [5]. "Work" is not demonstrated for patches in the peer-reviewed record.
Is NAD safe?
Oral precursors were generally well tolerated in trials [4][3], but safety differs by route. IV and injectable NAD+ is compounded and unapproved; infusions can cause flushing or chest and abdominal discomfort if run too fast, and a compounded injectable was recalled (Class I) for endotoxin [5]. Safety is route-dependent, not a single answer.
What is the best time to take NAD, morning or night?
No trial has established an optimal time of day. NAMPT, the rate-limiting salvage enzyme, follows a circadian rhythm and is induced by exercise [13], but that is mechanistic biology, not a validated timing protocol. The literature supports no specific morning-versus-night recommendation.
How long do NAD side effects last?
Infusion-related effects such as flushing or chest and abdominal discomfort are described in connection with the infusion itself and ease when the rate is slowed [5]. Published trials did not report persistent adverse effects [4][3], but durations are not systematically characterized in the literature.