Side-Effects: While the signs of a great body may make one think that there cannot be anything wrong with bodybuilding supplements, the facts speak otherwise. Bodybuilding supplements do have side-effects and you must listen to your trainer before giving in to the thoughts of buying one. Creatine can cause heart problems, kidney problems, dehydration, diarrhoea and muscle cramping. You must also discuss your medical history with the trainer. 
Muscle building supplements can serve as a great tool for helping you increase your muscle mass.  Always remember that, as when taking any supplement, it’s best to consult with your doctor to ensure that you won’t face any adverse interactions with medications or negatively affect your health. While the muscle building supplements listed are all generally safe, individuals with chronic health conditions should be especially careful.
^ Jump up to: a b c Brioche T, Pagano AF, Py G, Chopard A (April 2016). "Muscle wasting and aging: Experimental models, fatty infiltrations, and prevention". Mol. Aspects Med. 50: 56–87. doi:10.1016/j.mam.2016.04.006. PMID 27106402. In conclusion, HMB treatment clearly appears to be a safe potent strategy against sarcopenia, and more generally against muscle wasting, because HMB improves muscle mass, muscle strength, and physical performance. It seems that HMB is able to act on three of the four major mechanisms involved in muscle deconditioning (protein turnover, apoptosis, and the regenerative process), whereas it is hypothesized to strongly affect the fourth (mitochondrial dynamics and functions). Moreover, HMB is cheap (~30– 50 US dollars per month at 3 g per day) and may prevent osteopenia (Bruckbauer and Zemel, 2013; Tatara, 2009; Tatara et al., 2007, 2008, 2012) and decrease cardiovascular risks (Nissen et al., 2000). For all these reasons, HMB should be routinely used in muscle-wasting conditions especially in aged people. ... 3 g of CaHMB taken three times a day (1 g each time) is the optimal posology, which allows for continual bioavailability of HMB in the body (Wilson et al., 2013).
This suppression of creatine synthesis is thought to actually be beneficial, since creatine synthesis requires s-adenosyl methionine as a cofactor and may use up to 40-50% of SAMe for methylation[35][36][122] (initially thought to be above 70%, but this has since been re-evaluated[122]) though the expected preservation of SAMe may not occur with supplementation.[487] Reduced creatine synthesis, via preserving methyl groups and trimethylglycine (which would normally be used up to synthesize SAMe), is also thought to suppress homocysteine levels in serum,[37] but this may also not occur to a practical level following supplementation.[487]
Safety. Iron overload may cause a disease called hemochromatosis in some susceptible people. Iron supplements should only be prescribed by a doctor, and for athletes or those who train heavily, a sports physician combined with a sports dietitian may be preferable. Be sure to take care with this because iron supplements should not be taken casually. Iron supplements may cause constipation and gastric upset in some people.
Collectively the above investigations indicate that creatine supplementation can be an effective strategy to maintain total creatine pool during a rehabilitation period after injury as well as to attenuate muscle damage induced by a prolonged endurance training session. In addition, it seems that creatine can act as an effective antioxidant agent after more intense resistance training sessions.