On lighter to medium skin tones, solar lentigenes emerge as small- to medium-sized brown patches of freckling that can grow and accumulate over time on areas of the body that receive the most unprotected sun exposure, such as the back of the hands, forearms, chest, and face. For those with darker skin colors, these discolorations can appear as patches or areas of ashen-gray skin. Exposure to the Sun
Melanin in the skin protects the body by absorbing solar radiation. In general, the more melanin there is in the skin the more solar radiation can be absorbed. Excessive solar radiation causes direct and indirect DNA damage to the skin and the body naturally combats and seeks to repair the damage and protect the skin by creating and releasing further melanin into the skins cells. With the production of the melanin, the skin color darkens, but can also cause sunburn. The tanning process can also be created by artificial UV radiation. There are two different mechanisms involved. Firstly, the UVA-radiation creates oxidative stress, which in turn oxidizes existing melanin and leads to rapid darkening of the melanin, also known as IPD (immediate pigment darkening). Secondly, there is an increase in production of melanin known as melanogenesis. Melanogenesis leads to delayed tanning and first becomes visible about 72 hours after exposure. The tan that is created by an increased melanogenesis lasts much longer than the one that is caused by oxidation of existing melanin.
Spectrum of bacterial susceptibility
Aerobic Gram-positive bacteria

Staphylococcus aureus
Streptococcus pneumoniae
Streptococcus pyogenesAerobic Gram-negative bacteria

Haemophilus parainfluenzae 
Haemophilus influenzae
Moraxella catarrhalisHelicobacter

Helicobacter pyloriMycobacteria
Mycobacterium avium complex consisting of:

Mycobacterium avium avium
Mycobacterium intracellulareOther bacteria

Chlamydia pneumoniae
Mycoplasma pneumoniaeSafety and effectiveness of clarithromycin in treating clinical infections due to the following bacteria have not been established in adequate and well-controlled clinical trials:Aerobic Gram-positive bacteria

Streptococcus agalactiae
Streptococcus (Groups C, F, G)
Viridans group streptococciAerobic Gram-negative bacteria

Bordetella pertussis
Legionella pneumophila
Pasteurella multocidaAnaerobic Gram-positive bacteria

Clostridium perfringens
Peptococcus Niger
Cutibacterium acnesAnaerobic Gram-negative bacteria

Prevotella melaninogenica (formerly Bacteroides melaninogenicus)

Contraindications
Clarithromycin should not be taken by people who are allergic to other macrolides or inactive ingredients in the tablets, including microcrystalline cellulose, croscarmelose sodium, magnesium stearate, and povidone
Clarithromycin should not be used by people with a history of cholestatic jaundice and/or liver dysfunction associated with prior clarithromycin use. Clarithromycin should not be used in the setting of hypokalaemia (low blood potassium)
Use of clarithromycin with the following medications: cisapride, pimozide, astemizole, terfenadine, ergotamine, ticagrelor, ranolazine or dihydroergotamine is not recommended. It should not be used with colchicine in people with kidney or liver impairment. Concomitant use with cholesterol medications such as lovastatin or simvastatin. Hypersensitivity to clarithromycin or any component of the product, erythromycin, or any macrolide antibiotics. QT prolongation or ventricular cardiac arrhythmias, including torsade de pointes. Side effects
The most common side effects are gastrointestinal: diarrhea (3%), nausea (3%), abdominal pain (3%), and vomiting (6%). It also can cause headaches, insomnia, and abnormal liver function tests. Allergic reactions include rashes and anaphylaxis.